CN109980614A - A kind of distribution line zero-sequenceprotection direction-adaptive method of discrimination - Google Patents
A kind of distribution line zero-sequenceprotection direction-adaptive method of discrimination Download PDFInfo
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- CN109980614A CN109980614A CN201910251589.5A CN201910251589A CN109980614A CN 109980614 A CN109980614 A CN 109980614A CN 201910251589 A CN201910251589 A CN 201910251589A CN 109980614 A CN109980614 A CN 109980614A
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- phase
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- sequenceprotection
- distribution line
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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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Abstract
The present invention relates to the technical fields of circuit protection; more specifically; it is related to a kind of distribution line zero-sequenceprotection direction-adaptive method of discrimination; distribution line puts into operation when taking load, puts into CT polarity automatic detection function, compares the phase difference of three-phase CT phase current Ip and phase voltage Up; it is compared with the load current direction manually set and judges CT polarity; if CT polarity is reversed, three-phase CT polarity is negated automatically, route puts into operation backed off after random CT polarity automatic detection function and load current direction；When ground fault occurs for route, more self-produced 3U0And 3I0Phase difference, and zero-sequenceprotection discriminating direction is carried out according to phase difference.The present invention can be avoided the too small problem for causing zero sequence current measurement precision deficiency of self-produced two sub-value of zero-sequence current; zero-sequenceprotection discriminating direction uses self-produced zero-sequence current and self-produced residual voltage; and three-phase CT has been verified that polarity in on-load, effectively avoids the reversed risk for causing tripping of zero sequence CT polarity.
Description
Technical field
The present invention relates to the technical fields of circuit protection, certainly more particularly, to a kind of distribution line zero-sequenceprotection direction
Adapt to method of discrimination.
Background technique
10kV~66kV Neutral Grounding Method of Power Distribution System and power supply reliability, Overvoltage and insulation coordination, relay are protected
Shield etc. is closely related, is to ensure the person, equipment and the essential condition of the reliable and stable operation of power system security.Currently, in distribution
Neutral grounding mode is widely used in system, and there are several types of (1) isolated neutral modes；(2) neutral point is through arc blowout wire
Enclose earthing mode；(3) Neutral Point Through Low Resistance mode；(4) neutral point is through arc suppression coil parallel low resistance joint grounding side
Formula；(5) failure is mutually through earthing modes such as low reactance ground connection.Wherein with neutral by arc extinction coil grounding, neutral point through small resistance
Earthing mode is most commonly seen.The major advantage of arc suppression coil earthing system can operate with failure when being single-phase fault, guarantee to supply
Electric reliability, while cooperating line-selected earthing device, failure is searched for operations staff, and technical support is provided.
In most of supplying power allocation system, due to only one grounding point of system, zero-sequenceprotection generally not incidence,
But in part core city power supply area, due to being powered using full cable, line capacitance electric current is larger, especially when using 20kV
When voltage class is powered, line capacitance electric current is more obvious, up to 3A/ kilometers；Simultaneously as 20kV line powering capacity and half
Diameter is all bigger than 10kV route, often occur II sections of definite values of zero-sequenceprotection can not hide line capacitance electric current the case where, it is necessary to carry out
Zero-sequenceprotection discriminating direction.The zero-sequenceprotection of 10kV or 20kV distribution line according to self-produced zero sequence current mutual inductor (CT), due to
Phase current CT no-load voltage ratio is larger, two sub-value very little of zero-sequenceprotection definite value, in addition uses self-produced zero sequence CT, when single-phase CT broken string occurs
It may cause zero-sequenceprotection malfunction, therefore the zero-sequenceprotection of 10kV or 20kV distribution line preferably uses external zero sequence CT；And it uses
External zero sequence CT will lead to following problems:, can not be when putting into operation since zero-sequence current only just occurs when ground fault occurs
Hexagonal figure, which is surveyed, by normal load current verifies whether zero sequence CT polarity is correct, and there are tripping wind for the zero-sequenceprotection with direction
Danger.
Summary of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide a kind of distribution line zero-sequenceprotection direction-adaptives
Method of discrimination solves the reversed risk for causing tripping of the external zero sequence CT polarity of distribution line.
In order to solve the above technical problems, the technical solution adopted by the present invention is that:
A kind of distribution line zero-sequenceprotection direction-adaptive method of discrimination is provided, on route to be discriminated configured with three-phase CT,
External zero sequence CT and with can throw move back CT polarity automatic detection function and can assumed load current direction function protective device,
The method of discrimination the following steps are included:
S10. the size and phase of phase current Ip and phase voltage Up are collected and recorded by three-phase CT；
S20. when distribution line, which puts into operation, takes load, the three-phase CT polarity automatic detection function is put into, compares mutually electricity
Flow the phase difference of Ip and phase voltage Up；The load current direction is manually set, protective device compares phase current Ip and phase automatically
The phase difference of voltage Up calculates three-phase CT sample rate current direction, and compared with actual load current direction, if charged with actual negative
It is consistent to flow direction, then is determined as that CT polarity is correct, if on the contrary, if be determined as that CT polarity is reversed, and three-phase CT polarity is taken automatically
Instead；
S30. after the completion of distribution line puts into operation, CT polarity automatic detection function and load current direction setting function are exited
Can, erroneous judgement when avoiding load current direction change；
S40. when ground fault occurs for distribution line, differentiate whether the external zero sequence CT sample rate current is greater than zero sequence guarantor
Shield acts definite value, while comparing the self-produced residual voltage 3U of protective device0With self-produced zero-sequence current 3I0Phase difference, and according to phase
Potential difference determine zero-sequence current direction, then allow if positive direction zero-sequenceprotection movement tripping, on the contrary it is then be latched zero-sequenceprotection act
Tripping.
Distribution line zero-sequenceprotection direction-adaptive method of discrimination of the invention, zero-sequenceprotection size of current pass through external zero
Sequence CT uses current judgement, and zero-sequenceprotection direction is sentenced using the phase bit comparison of self-produced zero-sequence current and self-produced residual voltage
Not, three-phase CT automatic discrimination confirmation polarity when route puts into operation on-load is correct, solves distribution line under normal operating condition
The problem of zero sequence CT polarity can not verify, the risk of relay fail caused by avoiding because of distribution line zero sequence CT incorrect polarity, simultaneously
Three-phase CT polarity can automatic discrimination, improve working efficiency.
Preferably, the CT polarity automatic detection function throw by control word and be moved back: 1 is investment, and 0 is to exit.By controlling
Word throw and is moved back, and control logic is simple, it is easy to accomplish.
Preferably, the actual load current direction is manually set by control word: 1 flows to route for bus, and 2 be line
Road flows to bus, and 0 is to exit.It is configured by control word, control logic is simple, it is easy to accomplish.
Preferably, in step S20, if three-phase CT sample rate current direction is consistent with actual load current direction, it is determined as
CT polarity is correct；If three-phase CT sample rate current direction with actual load current direction on the contrary, if be determined as that CT polarity is reversed, and from
It is dynamic to negate three-phase CT polarity.Three-phase CT automatic discrimination confirmation polarity when route puts into operation on-load is correct, solves normal fortune
The problem of distribution line zero sequence CT polarity can not verify under row state avoids distribution line zero sequence CT incorrect polarity and causes to protect
The risk of tripping.
Preferably, in step S20, phase current Ip and phase voltage Up phase difference CL Compare Logic are as follows:
When actual load electric current flows to route to be discriminated by bus: if -90 °+Δ≤arg (Up/Ip)≤90 °-Δ,
Confirm that CT polarity is correct；If -90 °+Δ≤arg (Ip/Up)≤90 °-Δ, confirming that CT polarity negates；
When actual load electric current flows to bus by route to be discriminated: if -90 °+Δ≤arg (Ip/Up)≤90 °-Δ,
Confirm that CT polarity is correct；If -90 °+Δ≤arg (Up/Ip)≤90 °-Δ, confirming that CT polarity is reversed.
Three-phase CT automatic discrimination confirmation polarity when route puts into operation on-load is correct, solves distribution under normal operating condition
The problem of route zero sequence CT polarity can not verify avoids the risk that distribution line zero sequence CT incorrect polarity causes relay fail,
Three-phase CT polarity automatic discrimination simultaneously improves working efficiency.
Preferably, in step S40, if distribution line zero-sequenceprotection action logic includes: 0 °+Δ≤arg (3I0/3U0)≤
180 °-Δ, then zero-sequenceprotection positive direction acts, and zero-sequenceprotection is allowed to export tripping；It is on the contrary then be latched zero sequence outlet tripping.Zero sequence
Size of current uses external zero sequence CT sample rate current, and zero-sequence current discriminating direction uses self-produced zero-sequence current and self-produced residual voltage
Phase bit comparison differentiated solve the problems, such as not verifying zero sequence CT polarity under normal condition.
Compared with prior art, the beneficial effects of the present invention are:
Distribution line zero-sequenceprotection direction-adaptive method of discrimination of the invention, since the size of current of zero-sequenceprotection uses
It is external, avoid the too small problem for causing zero-sequence current sampling precision deficiency of self-produced two sub-value of zero-sequence current；Sentence in zero-sequenceprotection direction
Cai Yong not be self-produced, and three-phase CT has been verified that polarity in on-load, avoids the reversed risk for causing tripping of zero sequence CT polarity；
And three-phase CT polarity automatic discrimination of the invention, working efficiency can be improved.
Detailed description of the invention
Fig. 1 is the flow diagram of distribution line zero-sequenceprotection direction-adaptive method of discrimination of the invention；
Fig. 2 is three-phase CT polarity discriminating active region schematic diagram when load current flows to route to be discriminated by bus；
Fig. 3 is three-phase CT polarity discriminating active region schematic diagram when load current flows to bus by route to be discriminated；
Fig. 4 is zero-sequenceprotection discriminating direction active region schematic diagram.
Specific embodiment
The present invention is further illustrated With reference to embodiment.Wherein, attached drawing only for illustration,
What is indicated is only schematic diagram, rather than pictorial diagram, should not be understood as the limitation to this patent；Reality in order to better illustrate the present invention
Example is applied, the certain components of attached drawing have omission, zoom in or out, and do not represent the size of actual product；To those skilled in the art
For, the omitting of some known structures and their instructions in the attached drawings are understandable.
The same or similar label correspond to the same or similar components in the attached drawing of the embodiment of the present invention；It is retouched in of the invention
In stating, it is to be understood that if the orientation or positional relationship for having the instructions such as term " on ", "lower", "left", "right" is based on attached drawing
Shown in orientation or positional relationship, be merely for convenience of description of the present invention and simplification of the description, rather than indication or suggestion is signified
Device or element must have a particular orientation, be constructed and operated in a specific orientation, therefore positional relationship is described in attached drawing
Term only for illustration, should not be understood as the limitation to this patent, for the ordinary skill in the art, can
To understand the concrete meaning of above-mentioned term as the case may be.
Embodiment
It is as shown in Figure 1 the embodiment of distribution line zero-sequenceprotection direction-adaptive method of discrimination of the invention, it is to be discriminated
Configured with three-phase CT, external zero sequence CT and have to throw and move back CT polarity automatic detection function and can assumed load electric current on route
The protective device of direction function.Wherein, the CT polarity automatic detection function throw by control word and be moved back: 1 is investment, and 0 is to move back
Out；Actual load current direction can be set by control word: 1 flows to route for bus, and 2 flow to bus for route, and 0 is to move back
Out.Throw by control word and move back, control logic is simple, it is easy to accomplish.
The method of discrimination the following steps are included:
S10. the size and phase of phase current Ip and phase voltage Up are collected and recorded by three-phase CT；
S20. when distribution line, which puts into operation, takes load, the three-phase CT polarity automatic detection function is put into, compares mutually electricity
Flow the phase difference of Ip and phase voltage Up；Artificial setting actual load current direction, the three-phase CT sample rate current direction with
Actual load current direction simultaneously determines three-phase CT polarity, if polarity is reversed, automatically negates three-phase CT polarity.
The specific control logic of step S20 is as follows:
When actual load electric current flows to route to be discriminated by bus: if -90 °+Δ≤arg (Up/Ip)≤90 °-Δ,
Confirm that CT polarity is correct；If -90 °+Δ≤arg (Ip/Up)≤90 °-Δ, confirming that CT polarity negates, three-phase CT polarity discriminating
Element movement area is as shown in Figure 2；
When actual load electric current flows to bus by route to be discriminated: if -90 °+Δ≤arg (Ip/Up)≤90 °-Δ,
Confirm that CT polarity is correct；If -90 °+Δ≤arg (Up/Ip)≤90 °-Δ, confirming that CT polarity is reversed, three-phase CT polarity discriminating
Element movement is as shown in Figure 3.
S30. after the completion of distribution line puts into operation, polarity automatic detection function and load current direction set-up function are exited,
Erroneous judgement when actual load current direction being avoided to change；
S40. when ground fault occurs for distribution line, differentiate whether the zero sequence CT sample rate current is dynamic greater than zero-sequenceprotection
Make definite value, while comparing the self-produced residual voltage 3U of protective device0With self-produced zero-sequence current 3I0Phase difference, and according to phase difference into
Row zero-sequenceprotection discriminating direction.
The specific control logic of step S40 is as follows:
If 0 °+Δ≤arg (3I0/3U0)≤180 °-Δ, then zero-sequenceprotection positive direction acts, and allows zero-sequenceprotection to export and jumps
Lock；It is on the contrary then be latched zero sequence outlet tripping；Zero-sequenceprotection direction active region is as shown in Figure 4.
By above step, solve the problems, such as that distribution line zero sequence CT polarity can not verify under normal operating condition, avoid
Distribution line zero sequence CT incorrect polarity causes the risk of relay fail, at the same three-phase CT polarity can automatic discrimination, improve work
Efficiency.
Obviously, the above embodiment of the present invention be only to clearly illustrate example of the present invention, and not be pair
The restriction of embodiments of the present invention.For those of ordinary skill in the art, may be used also on the basis of the above description
To make other variations or changes in different ways.There is no necessity and possibility to exhaust all the enbodiments.It is all this
Made any modifications, equivalent replacements, and improvements etc., should be included in the claims in the present invention within the spirit and principle of invention
Protection scope within.
Claims (6)
1. a kind of distribution line zero-sequenceprotection direction-adaptive method of discrimination, which is characterized in that be connected with three on route to be discriminated
Phase CT, external zero sequence CT and with can throw move back CT polarity automatic detection function and can assumed load current direction function protection
Device, the method for discrimination the following steps are included:
S10. the size and phase of phase current Ip and phase voltage Up are collected and recorded by three-phase CT；
S20. when distribution line, which puts into operation, takes load, protective device puts into CT polarity automatic detection function, compares phase current Ip
And the phase difference of phase voltage Up, three-phase CT sample rate current direction is calculated, and compared with actual load current direction: and if actual negative
Charged current direction is consistent, then is determined as that CT polarity is correct；If on the contrary, if be determined as that CT polarity is reversed, and automatically by the pole three-phase CT
Property negates；
S30. after the completion of distribution line puts into operation, protective device exits CT polarity automatic detection function and the setting of load current direction
Function, erroneous judgement when actual load current direction being avoided to change；
S40. when ground fault occurs for distribution line, differentiate whether the external zero sequence CT sample rate current is dynamic greater than zero-sequenceprotection
Make definite value, while comparing the self-produced residual voltage 3U of protective device0With self-produced zero-sequence current 3I0Phase difference, and according to phase difference
Determine zero-sequence current direction.
2. distribution line zero-sequenceprotection direction-adaptive method of discrimination according to claim 1, which is characterized in that the CT
Polarity automatic detection function throw by control word and be moved back: 1 is investment, and 0 is to exit.
3. distribution line zero-sequenceprotection direction-adaptive method of discrimination according to claim 1, which is characterized in that the reality
Border load current direction is manually set by control word: 1 flows to route for bus, and 2 flow to bus for route, and 0 is to exit.
4. distribution line zero-sequenceprotection direction-adaptive method of discrimination according to any one of claims 1 to 3, feature exist
In if three-phase CT sample rate current direction is consistent with actual load current direction, being determined as that CT polarity is correct in step S20；If
Three-phase CT sample rate current direction with actual load current direction on the contrary, be then determined as that CT polarity is reversed, and automatically by the pole three-phase CT
Property negates.
5. distribution line zero-sequenceprotection direction-adaptive method of discrimination according to claim 4, which is characterized in that step
In S20, phase current Ip and phase voltage Up phase difference CL Compare Logic are as follows:
When load current flows to route to be discriminated by bus: if -90 °+Δ≤arg (Up/Ip)≤90 °-Δ, confirms the pole CT
Property is correct；If -90 °+Δ≤arg (Ip/Up)≤90 °-Δ, confirming that CT polarity negates；
When load current flows to bus by route to be discriminated: if -90 °+Δ≤arg (Ip/Up)≤90 °-Δ, confirms the pole CT
Property is correct；If -90 °+Δ≤arg (Up/Ip)≤90 °-Δ, confirming that CT polarity is reversed.
6. distribution line zero-sequenceprotection direction-adaptive method of discrimination according to claim 1, which is characterized in that step
In S40, distribution line zero-sequenceprotection discriminating direction logic are as follows: if 0 °+Δ≤arg (3I0/3U0)≤180 °-Δ, then zero-sequenceprotection
Positive direction movement, allows zero-sequenceprotection to export tripping；It is on the contrary then be latched zero-sequenceprotection outlet tripping.
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| CN110927631A (en) * | 2019-12-03 | 2020-03-27 | 陕西省地方电力（集团）有限公司宝鸡供电分公司 | Polarity judgment method for zero-sequence current transformer |
| CN111725778A (en) * | 2020-05-27 | 2020-09-29 | 湖南省湘电试验研究院有限公司 | Line protection CT disconnection locking method, system and medium under condition of reversed trend |
| CN112087048A (en) * | 2020-09-07 | 2020-12-15 | 西安热工研究院有限公司 | High-voltage plant branch zero-sequence protection configuration system and method |
| CN113872151A (en) * | 2021-09-08 | 2021-12-31 | 许继集团有限公司 | Protection method and protection device automatically adapting to polarity and phase sequence of overhead line |
| CN114200354A (en) * | 2022-02-16 | 2022-03-18 | 广东电网有限责任公司肇庆供电局 | Zero sequence CT polarity online detection method, system and equipment |
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| CN113872151A (en) * | 2021-09-08 | 2021-12-31 | 许继集团有限公司 | Protection method and protection device automatically adapting to polarity and phase sequence of overhead line |
| CN113872151B (en) * | 2021-09-08 | 2023-08-11 | 许继集团有限公司 | Protection method and protection device capable of automatically adapting to polarity and phase sequence of overhead line |
| CN114200354A (en) * | 2022-02-16 | 2022-03-18 | 广东电网有限责任公司肇庆供电局 | Zero sequence CT polarity online detection method, system and equipment |
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