CN108616109B - One kind differentiating excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method - Google Patents
One kind differentiating excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method Download PDFInfo
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- CN108616109B CN108616109B CN201810478055.1A CN201810478055A CN108616109B CN 108616109 B CN108616109 B CN 108616109B CN 201810478055 A CN201810478055 A CN 201810478055A CN 108616109 B CN108616109 B CN 108616109B
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- dsam
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- difference
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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
- H02H7/04—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 transformers
- H02H7/045—Differential protection of transformers
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
Abstract
The present invention discloses one kind and differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method, comprising the following steps: step 1: two cycle difference stream Sudden Changing Rate I of calculatingDsam_Id: step 2: sentencing after going on business stream starting, first point of difference stream Startup time is denoted as k；Note two cycle voltage jump amount of k moment is UDsam(k)=Usam(k)‑Usam(k+sec_wave)；Step 3, if { UDsam(k)+UDsam(k-1) > ε or K2/K1 < λ, then sentencing out is at this time excitation surge current, Blocking Differential Protection；λ is constant, ε be the k moment, two voltage jump amounts of (k-1) moment and constant；The application can accurately identify excitation surge current and troubles inside the sample space, provide beneficial theoretical supplement for the optimization of transformer differential protection engineering practice；Present applicant proposes new criterion of the ratio of phase voltage Sudden Changing Rate and difference stream Sudden Changing Rate as reference quantity is used, time difference threshold deficiency can not be accurately arranged by overcoming existing time difference method criterion.
Description
Technical field
The present invention relates to the new methods for being applied to electric system protection device, specifically prevent transformer when dropping due to excitation
It shoves and causes the malfunction of differential protection.
Background technique
Differential protection is the main protection of current power transformer extensive utilization, but due to the influence of excitation surge current, is being become
The more difficult identification physical fault electric current of main transformer protection and excitation surge current, differential performance factor are lower when depressor drops.
By the research of domestic and international expert's last decade, formd in engineering practice at present secondary harmonic brake principle,
Several big methods such as angle of rupture principle, waveform symmetry principle, magnetic flux characteristic recognition methods, but it was verified that these principles are more or less
There is drawback.Secondary harmonic brake principle, as most popular excitation surge current recognition principle is used at present, realization is simple, can
Strong operability, but there is also significant limitation, as modern electric gradually develops to the target of large capacity, high voltage, when being
When internal fault current occurs for system, the content of harmonic wave is very big, especially second harmonic, thus inherently inhibits secondary humorous
The application of wave braking principle.Interrupted angle principle is simply direct, and anti-overexcitation ability is strong, but contemporary transformer uses Microcomputer Protection,
It implements and acquires a certain degree of difficulty, the cost of hardware greatly improves.Waveform symmetry principle detects the interval angle and wave of difference current
Width, but there is certain uncertainty, diversity, the ununified final conclusions of the selection of symmetry coefficient.Magnetic flux characteristic identification side
Method simplifies calculating process, improves recognition speed, but the leakage inductance of winding and excitation are difficult to obtain.In recent years, associated specialist
Many related works have been done in identification for excitation surge current, a series of new principles are proposed, such as energy information law, fuzzy mearue
Method, wave coefficient etc..Transformer such as based on energy information identifies excitation surge current, i.e. the energy of calculating fundamental wave and secondary humorous
Wave discriminates whether as excitation surge current or internal fault, but the program uses prony algorithm, need to introduce quantity of parameters progress
It calculates, it is sufficiently complex.There is expert to propose to carry out magnetizing inrush current discrimination method based on k additive-fuzzy measure method, there are fuzzy products
Divide the problem of value difficulty.There is scholar to propose a kind of transformer excitation flow recognition method based on waveform cross-correlation coefficient, but
This method needs mass data, differentiates that the time is slow, it is difficult to meet the requirement of differential action time.
When to normal transformer during no-load closing, difference stream be core sataration caused by exciting current, and exciting current go out
Now to lag behind voltage.Detection applies voltage and difference stream (being exactly the side electric current that closes a floodgate for idle-loaded switching-on) changes current moment out
Time difference, if this time difference is greater than certain threshold value, difference stream is normal excitation surge current, protection blocking；Transformation
When device breaks down, no matter the failure is that occur when transformer operates normally, when combined floodgate or in making process, voltage
With poor rheology dissolve current moment must be while.However the value of time difference is difficult to accurately determine in engineering.
Summary of the invention
In order to solve prior art problem, the present invention provides a kind of utilization phase voltage and poor stream Sudden Changing Rate ratio method differentiation is
No is excitation surge current, and calculation method is simple, overcomes prior art and introduces that parameter is more, calculates complicated defect.The present invention
Technical solution calculates fastly, can satisfy the requirement of differential action time.
To achieve the above objectives, the present invention is realized using following technical scheme.
One kind differentiating excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method, includes the following steps,
Step 1: calculating two cycle difference stream Sudden Changing Rate IDsam_Id:
IDsam_Id=Isam_Id-Isam_Id_sec_wave；
Isam_IdSampled value, I are flowed for differencesam_Id_sec_waveFor the sampled point difference stream of two weeks wavefront；
Calculate difference stream bump amount Idup=| Isam_Id|-|Isam_Id_threewave|, Isam_Id_threewaveFor the sampling of three weeks wavefront
Point difference stream；If continuous 3 points are greater than difference stream Sudden Changing Rate and start definite value IQDAnd IdupIt uprushes threshold value greater than poor stream, then sentences poor stream and open
It is dynamic, enter step 2；After the starting timing of difference stream is more than overtime threshold value, if difference stream fourier value is less than differential starting return definite value
IQD_ret, then poor stream starting returns；
Step 2: sentencing after going on business stream starting, first point of difference stream Startup time is denoted as k；Remember that two weeks k moment wave voltage is prominent
Variable is UDsam(k)=Usam(k)-Usam(k+sec_wave)；Usam(k) k moment voltage sample value, U are indicatedsam(k+sec_
Wave the voltage sample value after two cycle of k moment) is indicated；
Note two cycle difference stream of k moment sports IDsam_Id(k)=Isam_Id(k)-Isam_Id(k+sec_wave), note voltage is prominent
The voltage jump amount of variable k moment previous point is UDsam(k-1), the voltage jump amount of the first two point is UDsam(k-2)；
Isam_IdIt (k) is k time difference stream sampled value, Isam_IdIt (k+sec_wave) is the difference stream sampling after two cycle of k moment
Value；
Step 3, it enables
If | UDsam(k)|+|UDsam(k-1) | > ε or K2/K1 < λ, then sentencing out is at this time excitation surge current, is latched differential guarantor
Shield；λ is constant.ε be k moment and two voltage jump amounts of (k-1) moment and constant；IDsam_Id(k-1) previous for the k moment
Two cycle difference streams of a point are mutated, IDsam_Id(k-2) it is mutated for two cycle difference streams of the first two point.
When calculating, to prevent denominator is too small from causing calculated result inaccurate, carry out arranged below: if | IDsam_Id(k)
| < 0.01, then K1=2, if | UDsam(k) | < 0.01, then K2=0.05；If | UDsam(k)+UDsam(k-1)+UDsam(k-2)|<
0.01, then K1=2, if | IDsam_Id(k)|+|IDsam_Id(k-1)|+|IDsam_Id(k-2) | < 0.01, then K2=0.05.
More preferably, cycle 20ms, every 48 point sampling of cycle are suitable for interval PT.
More preferably, poor stream uprushes threshold value as 0.05IN(INFor rated current).
More preferably, ε takes 10-20V.
More preferably, λ takes 0.6-0.8.
More preferably, differential starting returns to definite value IQD_retValue is 0.95-0.98.
Beneficial effect of the present invention includes:
The present invention discloses one kind and differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method, can accurately know
Other excitation surge current and troubles inside the sample space, provide the optimization of transformer differential protection engineering practice；Present applicant proposes use phase voltage
New criterion of the ratio of Sudden Changing Rate and difference stream Sudden Changing Rate as reference quantity, when overcoming existing time difference method criterion can not be accurately arranged
Between poor threshold it is insufficient.
Detailed description of the invention
Fig. 1, which is that the application is a kind of, differentiates the starting of excitation surge current method difference stream based on phase voltage and difference stream Sudden Changing Rate ratio method
Criterion flow chart；
Fig. 2 is sampled point difference stream and sampled voltage waveform when transformer drops；
Fig. 3 is magnetizing inrush current discrimination flow chart.
Specific embodiment
The invention will be further described with reference to the accompanying drawing and by specific embodiment, and following embodiment is descriptive
, it is not restrictive, this does not limit the scope of protection of the present invention.
As shown in Figure 1, a kind of differentiate excitation surge current method, including following step based on phase voltage and difference stream Sudden Changing Rate ratio method
Suddenly,
Step 1: calculating two cycle difference stream Sudden Changing Rate IDsam_Id:
IDsam_Id=Isam_Id-Isam_Id_sec_wave；
Isam_IdSampled value, I are flowed for differencesam_Id_sec_waveFor the sampled point difference stream of two weeks wavefront；
Calculate difference stream bump amount Idup=| Isam_Id|-|Isam_Id_threewave|, Isam_Id_threewaveFor the sampling of three weeks wavefront
Point difference stream；If continuous 3 points are greater than difference stream Sudden Changing Rate and start definite value IQDAnd IdupIt uprushes threshold value 0.05I greater than poor streamN(specified electricity
Stream), then sentence difference stream starting, enters step 2；After difference stream starts timing more than overtime threshold value, if difference stream fourier value is less than differential
Starting returns to definite value IQD_ret, then poor stream starting returns to (progress difference stream starting judgement), and otherwise poor stream starts, and enters step 2；This
Embodiment time-out threshold value is 4s；Differential starting returns to definite value IQD_retValue is 0.95-0.98, the present embodiment value 0.95.
Fig. 2 is sampled point difference stream and sampled voltage waveform when transformer drops, and difference stream and phase voltage are not to increase simultaneously
, poor lumen is aobvious to lag behind phase voltage, has the regular hour poor.Difference stream increases after differential starting, inflection point occurs.It is more than utilization
Feature differentiates excitation surge current.
Step 2: sentencing after going on business stream starting, first point of difference stream Startup time is denoted as k；Remember that two weeks k moment wave voltage is prominent
Variable is UDsam(k)=Usam(k)-Usam(k+sec_wave)；Usam(k) k moment voltage sample value, U are indicatedsam(k+sec_
Wave the voltage sample value after two cycle of k moment) is indicated；
Note two cycle difference stream of k moment sports IDsam_Id(k)=Isam_Id(k)-Isam_Id(k+sec_wave), note voltage is prominent
The voltage jump amount of variable k moment previous point is UDsam(k-1), the voltage jump amount of the first two point is UDsam(k-2)；
Isam_IdIt (k) is k time difference stream sampled value, Isam_IdIt (k+sec_wave) is the difference stream sampling after two cycle of k moment
Value；
Step 3, it enables
As shown in figure 3, if | UDsam(k)|+|UDsam(k-1) | > ε or K2/K1 < λ, then sentencing out is at this time excitation surge current,
Blocking Differential Protection；λ is constant.ε takes 10-20V, ε be the k moment, two voltage jump amounts of (k-) moment and constant.λ takes
0.6-0.8, IDsam_Id(k-1) it is mutated for two cycle difference streams of k moment previous point, IDsam_IdIt (k-2) is two weeks of the first two point
The mutation of wave difference stream.
Transformer operate normally or the troubles inside the sample space moment, due to difference stream and phase voltage Sudden Changing Rate be simultaneously increase,
K2's and K1 should be suitable, and K2/K1 value flows Startup time in difference close to 1, and voltage jump has also just taken place, and voltage is prominent
The sum of variable the first two point is small, is less than 10V.So when criterion | UDsam(k)|+|UDsam(k-1) | > ε or K2/K1 < λ is discontented
Foot, will not be mistaken for excitation surge current.And when excitation surge current really occurs, difference stream mutation will be late by the mutation in phase voltage, K2
K1, difference stream and phase voltage trend will be less than and inflection point occur in difference stream Startup time, difference stream Sudden Changing Rate has the tendency that becoming larger, K2/K1 <
λ (λ takes 0.6-0.8) meets excitation surge current feature.And Startup time is flowed in difference, since voltage jump flows mutation hair in difference in advance
Raw, the sum of voltage jump amount the first two point increases, and is greater than 10V.So when criterion can accurately determine excitation surge current.
When calculating, to prevent denominator is too small from causing calculated result inaccurate, carry out arranged below: if | IDsam_Id(k)
| < 0.01, then K1=2, if | UDsam(k) | < 0.01, then K2=0.05；If | UDsam(k)+UDsam(k-1)+UDsam(k-2)|<
0.01, then K1=2, if | IDsam_Id(k)|+|IDsam_Id(k-1)|+|IDsam_Id(k-2) | < 0.01, then K2=0.05.
Cycle is 20ms, every 48 point sampling of cycle, is suitable for interval PT.
Those skilled in the art can to the present invention be modified or modification design but do not depart from think of of the invention
Think and range.Therefore, if these modifications and changes of the present invention belongs to the claims in the present invention and its equivalent technical scope
Within, then the present invention is also intended to include these modifications and variations.
Claims (7)
1. one kind differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method, it is characterised in that:
Step 1: calculating two cycle difference stream Sudden Changing Rate IDsam_Id:
IDsam_Id=Isam_Id-Isam_Id_sec_wave；
Isam_IdSampled value, I are flowed for differencesam_Id_sec_waveFor the sampled point difference stream of two weeks wavefront；
Calculate difference stream bump amount Idup=| Isam_Id|-|Isam_Id_threewave|, Isam_Id_threewaveSampled point for three weeks wavefront is poor
Stream；If continuous 3 points are greater than difference stream Sudden Changing Rate and start definite value IQDAnd IdupIt uprushes threshold value greater than poor stream, then sentences difference stream starting, into
Enter step 2；After the starting timing of difference stream is more than overtime threshold value, if difference stream fourier value is less than differential starting return definite value IQD_ret, then
Difference stream starting returns；
Step 2: after difference stream starting, first point of difference stream Startup time is denoted as k；Note two cycle voltage jump amount of k moment is UDsam
(k)=Usam(k)-Usam(k+sec_wave)；Usam(k) k moment voltage sample value, U are indicatedsam(k+sec_wave) when indicating k
Voltage sample value after carving two cycles；
Note two cycle difference stream of k moment sports IDsam_Id(k)=Isam_Id(k)-Isam_Id(k+sec_wave), remember voltage jump amount k
The voltage jump amount of moment previous point is UDsam(k-1), the voltage jump amount of the first two point is UDsam(k-2)；
Isam_IdIt (k) is k time difference stream sampled value, Isam_IdIt (k+sec_wave) is difference stream sampled value after two cycle of k moment；
Step 3, it enables
If | UDsam(k)|+|UDsam(k-1) | > ε or K2/K1 < λ, then sentencing out is at this time excitation surge current, Blocking Differential Protection；λ
For constant, ε be k moment and two voltage jump amounts of (k-1) moment and constant；IDsam_IdIt (k-1) is k moment previous point
Two cycle difference streams mutation, IDsam_Id(k-2) it is mutated for two cycle difference streams of the first two point.
2. one kind according to claim 1 differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method,
It is characterized in that,
When calculating, to prevent denominator is too small from causing calculated result inaccurate, carried out it is arranged below, if | IDsam_Id(k)|<
0.01, then K1=2, if | UDsam(k) | < 0.01, then K2=0.05；If | UDsam(k)+UDsam(k-1)+UDsam(k-2) | < 0.01,
Then K1=2, if | IDsam_Id(k)|+|IDsam_Id(k-1)|+|IDsam_Id(k-2) | < 0.01, then K2=0.05.
3. one kind according to claim 1 differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method,
It is characterized in that,
The cycle is 20ms, and every 48 point sampling of cycle is suitable for interval PT.
4. one kind according to claim 1 differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method,
It is characterized in that,
Poor stream uprushes threshold value as 0.05IN, INFor rated current.
5. one kind according to claim 1 differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method,
It is characterized in that,
ε takes 10-20V.
6. one kind according to claim 1 differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method,
It is characterized in that,
λ takes 0.6-0.8.
7. one kind according to claim 1 differentiates excitation surge current method based on phase voltage and difference stream Sudden Changing Rate ratio method,
It is characterized in that,
Differential starting returns to definite value IQD_retValue is 0.95-0.98.
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| CN109638780B (en) * | 2019-01-08 | 2020-04-07 | 广东电网有限责任公司 | Control method of protection device |
| CN112698246A (en) * | 2020-12-31 | 2021-04-23 | 中国电力科学研究院有限公司 | Transformer excitation inrush current identification method and device based on current abrupt change |
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| CN102097785A (en) * | 2010-12-30 | 2011-06-15 | 清华大学 | Method for authenticating sympathetic inrush current in traction substation transformer |
| CN104319737A (en) * | 2014-10-30 | 2015-01-28 | 国网宁夏电力公司电力科学研究院 | Differential protection configuration method and device for sending transformer out of double-feed type wind field |
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| WO2012061978A1 (en) * | 2010-11-09 | 2012-05-18 | Abb Research Ltd. | Synchronization method for current differential protection |
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|---|---|---|---|---|
| CN102097785A (en) * | 2010-12-30 | 2011-06-15 | 清华大学 | Method for authenticating sympathetic inrush current in traction substation transformer |
| CN104319737A (en) * | 2014-10-30 | 2015-01-28 | 国网宁夏电力公司电力科学研究院 | Differential protection configuration method and device for sending transformer out of double-feed type wind field |
Non-Patent Citations (1)
| Title |
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| 换流变压器差动保护异常动作行为分析及对策;翁汉琍，林湘宁;《中国电机工程学报》;20091105;第29卷(第31期);全文 |
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