CN109802359B - Relay protection method for preventing damage to transformer due to flashover of circuit breaker - Google Patents
Relay protection method for preventing damage to transformer due to flashover of circuit breaker Download PDFInfo
- Publication number
- CN109802359B CN109802359B CN201910168425.6A CN201910168425A CN109802359B CN 109802359 B CN109802359 B CN 109802359B CN 201910168425 A CN201910168425 A CN 201910168425A CN 109802359 B CN109802359 B CN 109802359B
- Authority
- CN
- China
- Prior art keywords
- protection
- flashover
- transformer
- circuit breaker
- breaker
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Supply And Distribution Of Alternating Current (AREA)
- Gas-Insulated Switchgears (AREA)
Abstract
the invention discloses a relay protection method for preventing a transformer from being damaged due to flashover of a circuit breaker. The method protects all adjacent circuit breakers which act to trip circuit breakers with flashover, and does not start circuit breaker failure protection. The protection method is suitable for protecting the high-voltage side grid-connected circuit breaker of the transformer of the generator-transformer bank without a generator-side circuit breaker, the protection action delay is 100ms, and all adjacent circuit breakers of the circuit breaker generating flashover are guaranteed to be developed in a trip within 250 ms. In the existing protection method, the time delay from the flashover protection starting of the circuit breaker to the failure protection outlet is generally long, and the damage of the transformer is often caused. The invention integrates circuit breaker protection and transformer protection, after the circuit breaker flashover, all adjacent circuit breakers are directly tripped off, the fault isolation within 250ms is realized, the expansion of the fault range is avoided, and the transformer is ensured not to be damaged, and the invention obtains the part 5 of the national standard GB1094.5-2008 power transformer: the capability of bearing short circuit has great application value through the support of theory and test.
Description
Technical Field
The invention belongs to the technical field of relay protection of power systems, and particularly relates to a relay protection method for preventing a transformer from being damaged due to flashover of a circuit breaker.
background
In the process that the generator-transformer set is connected with the power grid through the booster transformer high-voltage side circuit breaker, the voltage difference on the fracture of the circuit breaker continuously changes along with the change of the angle difference between the system voltage on the two sides of the fracture and the no-load voltage of the generator-transformer set, and when a certain phase angle difference is 180 degrees, the voltage difference of 2 times of the operating voltage can be generated on the two sides of the fracture. At the moment, if the internal insulation of the circuit breaker has defects or the external insulation of the circuit breaker has dirt, the flashover accident of the circuit breaker is very easy to develop. Some domestic power plants have the problems of equipment aging and partial insulation failure of the circuit breaker due to long commissioning time (more than 15 years), so that the situation of flashover of the circuit breaker is greatly increased.
Breaker flashover faults require removal by breaker flashover protection. The action condition for circuit breaker flashover protection is that the circuit breaker is in the open position and a negative sequence current is present, which has been recognized in the industry. However, there is still much debate on the action time and the action mode of flashover protection. At present, the commonly adopted method is based on the 'relay protection setting calculation guide rule of a large generator transformer', namely when a breaker is not arranged at a machine end, the breaker failure protection is started while the breaker is de-energized.
According to the classical theory of the generator, even if the magnetic field breaker is timely disconnected after the generator is de-energized, due to the influence of the inductance of the excitation loop, the excitation loop of the generator has an impact voltage in the opposite direction at the moment of the disconnection of the magnetic field breaker, and the maximum value can reach a rated value which is several times. This current is present in the excitation circuit, continues to maintain the stator voltage, and lasts for several seconds. Therefore, after the breaker is subjected to fracture flashover, according to the existing flashover protection method, even if flashover protection acts to extinguish magnetism, the voltage at the generator terminal cannot disappear immediately, the fault current still exists, and the fault state is not improved.
At the moment, the flashover fault of the circuit breaker can be removed only by the failure protection of the circuit breaker. For the time limit of failure protection, DL/T559-2007 operation setting regulation of 220 kV-750 kV power grid relay protection device 7.2.10.2 stipulates that in a double-bus connection mode, the circuit breaker acts on a bus-coupled or sectional circuit breaker in a short time limit (about 250-350 ms) and acts on all circuit breakers connected with the same bus with a circuit breaker which is disconnected and refused to act in a long time limit (about 500 ms); under the connection mode of the 3/2 circuit breaker, the three-phase circuit breaker and all circuit breakers related to the circuit breaker which rejects movement can be directly tripped within a time limit (about 200-500 ms), including the circuit breaker on the opposite side of the circuit breaker which is disconnected via a loop. And the circuit breakers on the tripping local side can be operated for three phases in a short time (about 130-150 ms), and all the circuit breakers related to the circuit breakers which are refused to be operated are tripped for a long time (about 200-250 ms), including the circuit breakers on the opposite side are disconnected through a remote tripping channel.
namely, the sum of the time delay from the flashover protection starting of the circuit breaker to the failure protection outlet is about 350-450 ms for the double-bus connection mode, and the time limit for tripping off the bus-coupled or segmented circuit breaker is about 500-600 ms for tripping off all circuit breakers on the bus on the side. For the 3/2 circuit breaker wiring mode, the time limit range of one setting mode is 300-700 ms, and all circuit breakers related to three-phase and refusal-action circuit breakers of the circuit breaker are jumped. In another setting mode, the time limit range is about 230-350 ms, and the circuit breaker operates to jump three phases of the circuit breaker on the local side; and tripping off all circuit breakers associated with the refusing circuit breaker at 300-450 ms.
the time limit is set to be more than 250ms from the initiation of flashover protection to the tripping of the associated circuit breaker by the failsafe. And according to GB1094.5-2008 "power transformer part 5: the capacity of bearing short circuit of the transformer is more than 2500kVA, and the transformer is not damaged when the short circuit delay is not more than 250ms, namely, if the accident duration exceeds 250ms, the transformer can be damaged. In addition, for the flashover fault, because the phases of the voltages on the two sides of the fracture are opposite, the current flowing through the transformer is 2 times of the short-circuit current when the power supplies on the two sides are in the same phase, and huge damage can be brought to the transformer in a short time.
Approximately 9s after a generator of a power plant in Jiangsu province is disconnected with a system in 2012, flashover of a phase A of a high-voltage side switch of a main transformer occurs, so that discharge to the ground is caused, the flashover protection action returns due to current attenuation, after the flashover protection action is carried out for the second time, failure protection is started, the accident is continuously developed due to long delay of the failure protection, and finally, complete arc extinguishing of a fault point is caused until the phase A switch of the main transformer is exploded after 1.6 s.
a circuit breaker flashover fault occurs on the C phase of a No. 2 main transformer high-voltage side 2502 circuit breaker of a certain power plant in Jiangsu province in 2014, 340ms after the flashover protection fault, a transformer winding is unstable and deformed, then short circuit grounding occurs, and finally, the actions of differential quick-break protection of the transformer, main transformer heavy gas protection and main transformer pressure release protection are caused in 379 ms.
A breaker flashover fault occurs in a first series 5013 breaker B phase of a booster station of a power plant in Guizhou province in 2014, a severe fault occurs in a main transformer after the flashover protection fault, 507ms main transformer heavy gas acts, 572ms main transformer differential protection and main transformer differential quick-break protection act.
aiming at the defects of the existing flashover protection method of the circuit breaker, some improved schemes or optimized methods are necessary to be provided, so that the flashover fault of the circuit breaker can be quickly isolated or cut off, and the huge economic loss caused by the damage of a transformer by fault current is avoided.
Disclosure of Invention
The invention aims to provide a relay protection method for preventing a transformer from being damaged due to flashover of a circuit breaker aiming at the defects of the existing flashover protection method of the circuit breaker, which is used for ensuring that the flashover fault of the circuit breaker can be isolated within 250ms so as to avoid huge economic loss caused by damage of the transformer due to fault current.
In order to achieve the purpose, the invention is realized by the following technical scheme:
A relay protection method for preventing a transformer from being damaged due to flashover of a circuit breaker comprises the following steps:
1) the protection device collects the current flowing through the protected circuit breaker and calculates the negative sequence current I 2;
2) When the protection device meets the following conditions, flashover protection is started;
(1) Putting a breaker flashover protection hard pressing plate into use;
(2) Putting a breaker flashover protection soft pressing plate into operation;
(3) Setting a flashover protection switching control word to be 1;
(4) the position of the breaker is in a separation position;
(5) The negative sequence current I 2 is greater than the flashover protection current fixed value threshold;
3) When flashover protection is started and delay time t passes, an flashover protection action outlet is formed;
4) Flashover protection acts to trip off all adjacent circuit breakers of the failed circuit breaker without initiating circuit breaker failure protection.
The further improvement of the invention is that in the step 3), the delay time t is 100ms, thereby reliably ensuring that all adjacent circuit breakers are tripped within 250ms after the circuit breakers generate flashover faults.
The invention is further improved in that the method is suitable for protecting the high-voltage side grid-connected circuit breaker of the transformer of the generator-transformer bank without a generator-end circuit breaker.
a further improvement of the invention is that all adjacent circuit breakers that the protection action trips comprise generator kill switches.
A further improvement of the invention consists in that, for a generator-transformer group which is grid-connected with a double-bus type, all the adjacent circuit breakers which the protection action trips comprise all the circuit breakers on the bus on which the generator-transformer group is located.
a further improvement of the invention consists in that, for a generator-transformer group with an 3/2 wiring type of grid-connected interrupters, all the adjacent circuit breakers that the protection action trips comprise two side circuit breakers on the string where the interrupters are located.
A further improvement of the invention consists in that, for generator-transformer groups with side breaker interconnection of the 3/2 wiring type, all the adjacent breakers to be tripped by the protection action include the middle breaker on the string where the side breaker is located and all the breakers on the bus where the side breaker is located.
The invention has the following beneficial technical effects:
1. The method is suitable for flashover protection of the circuit breaker, wherein the protection outlet mode is different from the traditional protection method, namely after flashover protection action, the process of starting the circuit breaker failure protection is skipped, and the adjacent circuit breaker of the circuit breaker which has flashover is directly tripped off, so that the fault can be quickly isolated (within 250ms), and the damage of a transformer is avoided.
2. The method provided by the invention considers that the flashover protection of the circuit breaker is the protection of the circuit breaker body, combines the circuit breaker protection and the transformer protection, and obtains the 5 th part of the national standard GB1094.5-2008 power transformer: the capability of bearing short circuit has great application value through the support of theory and test.
Compared with the prior art, the invention has the following remarkable advantages:
1. for flashover protection of a circuit breaker, the conventional method is according to the 'relay protection setting calculation guide rule of a large generator transformer', namely when a machine end has no circuit breaker, the action is carried out for deexcitation and the failure protection of the circuit breaker is started at the same time. After the generator is deexcited, the excitation current is slowly attenuated due to the influence of the inductance of the excitation loop, the stator of the generator lasts for several seconds, the fault current always exists, and the fault state is not improved. At the moment, the flashover fault of the circuit breaker can be removed only by the failure protection of the circuit breaker. However, the delay from the initiation of the breaker flashover protection to the failsafe egress is generally long. At this in-process, the flashover current of circuit breaker continuously develops, not only causes the damage that is difficult to restore to the circuit breaker body, and the transformer also can lose stability under huge electrodynamic force, takes place to warp, then the short circuit. The longer the duration, the greater the damage that is caused. The method for protecting the outlet of the transformer is different from the traditional protection method, namely after flashover protection action, the process of starting the breaker failure protection is skipped, and the adjacent breaker of the breaker which has flashover is directly tripped, so that the fault can be quickly isolated (within 250ms), and the transformer can be prevented from being damaged.
2. the method provided by the invention considers that the flashover protection of the circuit breaker is the protection of the circuit breaker body, integrates the circuit breaker protection and the transformer protection, and obtains the part 5 of the national standard GB1094.5-2008 power transformer: the capability of bearing short circuit has great application value through the support of theory and test.
Drawings
FIG. 1 is a protection logic diagram of the method of the present invention.
fig. 2 is a schematic diagram of a generator-transformer bank adopting a double-bus type grid connection.
Fig. 3 is a schematic diagram of a generator-transformer bank grid connected by 3/2 wiring.
The symbols in fig. 1 are illustrated as follows:
And represents a logical and relationship, i.e., its output is valid when its input conditions are all satisfied.
t denotes a delay time t milliseconds.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, the relay protection method for preventing damage to a transformer due to flashover of a circuit breaker provided by the invention comprises the following specific processes:
1. The protection device judges whether the flashover protection hard pressing plate of the circuit breaker is put into use.
2. the protection device judges whether the flashover protection soft pressing plate of the circuit breaker is put into use.
3. The protection device judges whether the flashover trip control word is set to '1'.
4. The protection device judges whether the position of the circuit breaker is positioned in the branch position.
5. When the steps 1, 2, 3 and 4 are all met, the protection device collects that the negative sequence current passing through the circuit breaker meets the action condition, and then the flashover protection of the circuit breaker is started.
6. The protection device passes through a small delay t action outlet, the delay is set according to the inconsistent time of the three phases of the circuit breaker, and the time can be taken as 100 ms.
7. the exit mode of the protection device is to jump all adjacent switches, and because the action time of the high-voltage circuit breaker and the de-excitation switch is extremely short, the requirement of less than 50ms is met, so that the total time delay from the flashover of the circuit breaker to the removal of the fault is not more than the part 5 of the national standard GB1094.5-2008 power transformer: the ability to withstand short circuits "required 250 ms.
8. For a generator-transformer set adopting a double-bus type grid connection, as shown in fig. 2, 1 is a bus tie breaker, 2 is a transformer, 3 is a generator, 4 is a field suppression switch, 5 is a first breaker, and 6 is a second breaker, if a flashover occurs in the grid connection of the first breaker 5, all adjacent breakers tripped at an outlet of the protection device should include the field suppression switch 4, the first breaker 5, the second breaker 6 and the bus tie breaker 1.
9. For the generator-transformer group which adopts 3/2 wiring type breaker grid connection, as shown in fig. 3, 7-10 are respectively the third to sixth breakers, the generator-transformer group adopts the third breaker 7 grid connection, if the third breaker 7 has flashover, all the adjacent breakers which are tripped by the outlet of the protection device should include the de-excitation switch 4, the first breaker 5 and the fifth breaker 9.
10. for a generator-transformer bank with an 3/2 wiring type side breaker grid connection, as shown in fig. 3, the generator-transformer bank is connected to the grid by a fifth breaker 9, and if the fifth breaker 9 is in flashover, all the adjacent breakers tripped by the outlet of the protection device should include the demagnetization switch 4, the third breaker 7 and the sixth breaker 10.
Claims (7)
1. A relay protection method for preventing a transformer from being damaged due to flashover of a circuit breaker is characterized by comprising the following steps of:
1) the protection device collects the current flowing through the protected circuit breaker and calculates the negative sequence current I 2;
2) When the protection devices all meet the following five conditions (1) to (5), flashover protection is started;
(1) Putting a breaker flashover protection hard pressing plate into use;
(2) Putting a breaker flashover protection soft pressing plate into operation;
(3) Setting a flashover protection switching control word to be 1;
(4) the position of the breaker is in a separation position;
(5) The negative sequence current I 2 is greater than the flashover protection current fixed value threshold;
3) When flashover protection is started and delay time t passes, an flashover protection action outlet is formed;
4) Flashover protection acts to trip off all adjacent circuit breakers of the failed circuit breaker without initiating circuit breaker failure protection.
2. The relay protection method for preventing the transformer from being damaged by the flashover of the circuit breaker according to claim 1, wherein in the step 3), the delay time t is 100ms, so that all adjacent circuit breakers are reliably guaranteed to be tripped open within 250ms after the flashover fault of the circuit breaker occurs.
3. the method of claim 1, wherein the method is applied to protection of a transformer high-side grid-connected circuit breaker of a generator-transformer set without a generator-side circuit breaker.
4. the relay protection method for preventing the transformer from being damaged by the flashover of the circuit breaker as claimed in claim 1, wherein in the step 4), all the adjacent circuit breakers tripped by the protection action comprise generator field suppression switches.
5. the relay protection method for preventing the transformer from being damaged by the flashover of the circuit breaker according to claim 1, wherein, for the generator-transformer set adopting the double-bus type grid connection, in the step 4), all the adjacent circuit breakers tripped by the protection action comprise all the circuit breakers on the bus where the generator-transformer set is positioned.
6. The relay protection method for preventing the transformer from being damaged by the flashover of the circuit breaker according to claim 1, wherein in the generator-transformer set which adopts the 3/2 wiring type breaker grid connection, in the step 4), all the adjacent circuit breakers which are tripped by the protection action comprise two side circuit breakers on the string of the breaker.
7. The relay protection method for preventing damage to the transformer due to breaker flashover according to claim 1, wherein in step 4), for the generator-transformer bank with 3/2 wiring type side breaker grid-connected, all adjacent breakers tripped by the protection action include the middle breaker on the string where the side breaker is located and all breakers on the bus where the side breaker is located.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910168425.6A CN109802359B (en) | 2019-03-06 | 2019-03-06 | Relay protection method for preventing damage to transformer due to flashover of circuit breaker |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910168425.6A CN109802359B (en) | 2019-03-06 | 2019-03-06 | Relay protection method for preventing damage to transformer due to flashover of circuit breaker |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109802359A CN109802359A (en) | 2019-05-24 |
| CN109802359B true CN109802359B (en) | 2019-12-10 |
Family
ID=66562530
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910168425.6A Active CN109802359B (en) | 2019-03-06 | 2019-03-06 | Relay protection method for preventing damage to transformer due to flashover of circuit breaker |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109802359B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112993944B (en) * | 2021-02-05 | 2022-10-21 | 西安热工研究院有限公司 | Flashover protection method for grid-connected circuit breaker of generator transformer bank |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104269824A (en) * | 2014-09-19 | 2015-01-07 | 国家电网公司 | Fault judgment method and backup protection method for medium-voltage side dead zone in main transformer |
-
2019
- 2019-03-06 CN CN201910168425.6A patent/CN109802359B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN109802359A (en) | 2019-05-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4477855A (en) | Protecting system for transmission lines | |
| CN110571761B (en) | Generation and transformation group protection method applied to international nuclear power million units | |
| CN107134762B (en) | A kind of based superconductive current limliting without arc dc circuit breaker and cutoff method | |
| CN112909903B (en) | High-voltage plant grounding protection and quick switching device protection starting combined optimization method | |
| CN103762551A (en) | Relay protection method for accelerated removal and TA sealing of dead zone faults of transformer based on open positions of circuit breakers | |
| CN111525525A (en) | Method and equipment for recovering power supply of downstream non-fault section with ground fault | |
| CN109802359B (en) | Relay protection method for preventing damage to transformer due to flashover of circuit breaker | |
| CN113555847B (en) | Dead zone protection method, device, equipment and medium for low-voltage branch of high-voltage plant | |
| CN109617031B (en) | Protection processing system for short circuit accident of power distribution network | |
| CN105790218B (en) | Prevent the main transformer backup protection of tripping from pressing off lock system and method again | |
| US20030030953A1 (en) | Method for automatically reclosing and an automatic reclosing device | |
| CN215817504U (en) | Motor soft start circuit and motor start cabinet | |
| KR100961171B1 (en) | The Protection Scheme for Asynchronizing of Power Generator | |
| Amaral et al. | On the application of a power electronics-based arc-flash suppressor | |
| CN110932228B (en) | Centralized reclosing method under breaker failure condition | |
| Lavaud et al. | Pyrotechnic current limiting devices—From design to operation | |
| Hara et al. | Fault protection of metallic return circuit of Kii channel HVDC system | |
| CN113725822A (en) | Method and system for removing fault of 220kV bus | |
| CN210780078U (en) | Power generation and supply network protection system | |
| JP3081494B2 (en) | Automatic section switch | |
| CN112564036B (en) | Reclosing method and device | |
| CN112993944B (en) | Flashover protection method for grid-connected circuit breaker of generator transformer bank | |
| CN113949046B (en) | Method for processing interphase short circuit of three-phase power system | |
| CN108736442B (en) | Line transformer group protection method and device | |
| RU2695643C1 (en) | Method of transforming power supply systems tn-cs and tt and power supply system for implementing method with protective input heterogeneous communication switching device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20191115 Address after: 710032 Shaanxi province Xi'an Beilin District Xingqing Road No. 136 Applicant after: Xi'an Thermal Power Research Institute Co., Ltd. Applicant after: Huaneng Group Technology Innovation Center Co., Ltd. Address before: 710032 No. 136, Xingqing Road, Xi'an, Shaanxi Applicant before: Xi'an Thermal Power Research Institute Co., Ltd. |
|
| TA01 | Transfer of patent application right | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |