CN106026022B - Power system excitation inrush current identification method based on reconstruct BH curvilinear characteristic - Google Patents
Power system excitation inrush current identification method based on reconstruct BH curvilinear characteristic Download PDFInfo
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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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The present invention provides a kind of power system excitation inrush current identification methods based on reconstruct BH curvilinear characteristic, excitation surge current is identified using the methods of second harmonic, waveform symmetry, but since technical principle is limited, there are still a large amount of malfunction cases, influence the normal operation of equipment.Pass through the further investigation to inductance component, BH curve is reconstructed using voltage and current, it is that magnetic induction density B axis reconstructs BH curve using horizontal direction as magnetic field strength H axis, vertical direction, according to the amesiality asymmetric feature of BH curve when excitation surge current, the reference frame constructed using new center D point as origin, plane where BH curve is divided into four quadrants by horizontal axis, the longitudinal axis in reference frame, then distributed number of the data point in four quadrants of reference frame on BH curve is counted respectively, and excitation surge current electric current is identified according to the graphic feature of BH curve.This recognition methods is using preceding without carrying out parameter setting and calculating; setting work before avoiding use has wide applicability, practical; it can be built in Microcomputer Protection product and be used as protection act criterion, improve the correctness and reliability of relay protection.
Description
Technical field
The invention belongs to technical field of power systems, and in particular to a kind of to be encouraged based on the electric system for reconstructing BH curvilinear characteristic
Magnetic inrush current identification method.
Background technique
In the power system, the induction equipments such as transformer, reactor, generator, motor are largely used, due to it
The saturated characteristic of internal silicon steel sheet causes these equipment to be easy to appear excitation surge current in operation.Such as the excitation surge current of transformer
Extreme case can achieve 7 times of rated current or more, and for protective device, excitation surge current and fault current all have electricity
The big feature of amplitude is flowed, such as fails correctly to identify, then is easy to cause the malfunction of protective relaying device, comprehensive various excitations at present are gushed
Stream recognition method can be classified as following three classes：
1. being shoved using the differentiation of transformer current amount, such as interval angle, secondary harmonic brake, waveform symmetry principle；
2. being shoved using the differentiation of transformer voltage amount, such as voltage braking principle；
3. being shoved simultaneously using transformer current and voltage differentiation, such as magnetic flux characteristic principle and equivalent circuit principle.
《New algorithm is differentiated based on magnetic flux and the transformer excitation flow of electric current asymmetry model of ellipse》（Southeast China University's journal
6th phase Zhao Yongbin in 2007 etc.）Excitation surge current is differentiated by the quasi- elliptical center point drift rate using poor magnetic flux and line current
And fault current；
《Transformer excitation flow based on flux path feature identifies new method》（Electric Power Automation Equipment 2008
12 phase Tan Jiang are flat）,《Transformer excitation flow is identified using flux path feature》（Relay the 2nd phase Zhao Xiao in 2014 is smooth
Deng）The track that transformer main flux is calculated using the transformer voltage and the magnitude of current of actual measurement, using maximum, minimum exciting current
Locate the difference of the sine value of flux path curve slope as the characteristic index for distinguishing excitation surge current and internal fault.
《Transformer excitation flow is identified based on virtual flux and differential current characteristics》（Automation of Electric Systems 2004
23rd phase Lee is rich and powerful etc.）Propose a kind of method based on the identification excitation surge current and internal short circuit fault that calculate virtual flux：
The point that 1/4 power frequency period is differed on 4 times is chosen, i.e. the point that two pairs of time phase differences were 1/2 period calculates in every a pair
Relative distance between two midpoints is defined as degree of asymmetry by point, by the degree of asymmetry being calculated and selected braking threshold
Value compares, the differentiation for carrying out failure and shoving.
Summary of the invention
Excitation surge current is identified using the methods of second harmonic, waveform symmetry, and protection caused by excitation surge current is avoided to miss
It is dynamic, but since technical principle is limited, there are still a large amount of malfunction cases, influence the normal operation of equipment.By to inductance component
Further investigation, provide it is a kind of based on reconstruct BH curvilinear characteristic power system excitation inrush current identification method.By to a certain
The voltage of electrical node, current data combined application reconstruct BH curve, are identified whether according to the graphic feature of BH curve to encourage
Magnetic shoves, and the recognition methods includes the following steps：High speed digital sample is carried out to voltage, the electric current on an electrical node, it will
Voltage, the electric current of fluctuation are converted to the sample data sequence for characterizing its change procedure；It is answered by the combination of voltage, current data
With, be by magnetic field strength H axis, vertical direction of horizontal direction magnetic induction density B axis reconstruct BH curve；It is found out on BH curve respectively
The maximum point A (H_max, B_max) of B axle, H axis direction, minimum point C (H_min, B_min) and new center D point；
Reference frame is constructed by origin of new center D point, plane where BH curve is divided by horizontal axis, the longitudinal axis in reference frame
Four quadrants；Then distributed number of the data point in four quadrants of reference frame on BH curve is counted respectively, is known accordingly
The graphic feature of other BH curve, to identify whether electric current is excitation surge current.
Preferably, D point coordinate is D in BH curve（X0, Y0）, wherein X0=(H_max+H_min)/2, Y0 = (B_
max + B_min) / 2。
Preferably, detailed process is as follows for reconstruct BH curve：
According to the sample rate of data, voltage, the current sampling data sequence of the previous complete cycle at this moment are intercepted, it is right
Voltage data sequence carries out the B_one_wave sequence obtained after Integral Processing, as the variation of magnetic induction density B, electric current
Variation of the data as H_one_wave sequence performance magnetic field strength H, on two-dimensional surface, using H_one_wave sequence as water
Square to magnetic field strength H axis coordinate data, coordinate of the B_one_wave sequence as the magnetic induction density B axis of vertical direction
Data are run a curve point by point using above-mentioned two groups of data sequences as BH curve.
Preferably, distributed number of the data point in four quadrants of reference frame on BH curve is counted, is identified accordingly
The graphic feature of BH curve, to identify that the step of whether electric current is excitation surge current is as follows：
The first step：H_one_wave, B_one_wave sequence are carried out to the array H_B_AXIS for being integrated into one two column, often
Corresponding two data of a line respectively indicate the corresponding X of a data point, Y axis coordinate；
Second step：Data scanning is carried out using the coordinate pair coordinate array H_B_AXIS of reference coordinate center D point, and is counted
Meet the quantity of the data point of following rule；
Positioned at reference frame first quartile：X > X0 And Y> Y0；
Positioned at the second quadrant of reference frame：X < X0 And Y> Y0；
Positioned at reference frame third quadrant：X < X0 And Y< Y0；
Positioned at reference frame fourth quadrant：X > X0 And Y< Y0；
The counter of four quadrant data points of synchronized update in scanning process：First quartile N1, the second quadrant N2, third as
Limit N3, fourth quadrant N4；
Third step：According to following feature, according to quantity of the data point on BH curve in four quadrants of reference frame
Distribution is to identify excitation surge current；
If some quadrant does not have BH curve to pass through, excitation surge current can be directly determined as when corresponding data point is zero；
If some quadrant has BH curve to pass through, when corresponding data point is not zero but numerical value is smaller, need according to first,
Three, two, the distribution comprehensive descision of four-quadrant, i.e., first, third quadrant, second, whether the ratio between the data point of fourth quadrant at certain
In a setting range, such as m1< N1/N3 <M2 and m1< N2/N4 <Judge between right and wrong excitation surge current when m2, is otherwise
Excitation surge current.
Preferably, m1=0.8, m2=1.2 are taken.
Beneficial effect
The present invention provides a kind of power system excitation inrush current identification methods based on reconstruct BH curvilinear characteristic, use voltage
Current data reconstructs BH curve, and analyzes the feature that BH curve is reconstructed under different conditions, according to BH curve when there is excitation surge current
Amesiality asymmetric feature carries out excitation surge current identification, can accurately identify excitation surge current.This recognition methods uses preceding nothing
Need to carry out parameter setting and calculating, the setting work before avoiding use has wide applicability, practical, can within
It sets and is used in Microcomputer Protection product as protection act criterion, improve the correctness and reliability of relay protection.
Detailed description of the invention
Fig. 1 is the BH curve reconstructed when transformer resistance loads；
Fig. 2 is the BH curve reconstructed when transformer inductance loads；
Fig. 3 is that transformer encourages the BH curve reconstructed when there is excitation surge current；
The BH curve that Fig. 4 is reconstructed when being transformer overexcitation；
Fig. 5 is the asymmetry recognition principle of BH curve
Fig. 6 is the excitation surge current recording occurred in Operation of Electric Systems
The variation of BH curve when Fig. 7 is the excitation surge current occurred in Operation of Electric Systems
Excitation surge current current recording waveform when Fig. 8 is Transformer Close
Excitation surge current corresponding reconstruct BH curve when Fig. 9 is Transformer Close
Specific embodiment
Present pre-ferred embodiments are provided with reference to the accompanying drawing, in order to explain the technical scheme of the invention in detail, specifically to become
The excitation surge current of depressor identifies to illustrate explanation.
Due to the differences such as transformer core remanent magnetism and switching-on phase angle, Transformer Close moment three-phase occurs of different sizes
Excitation surge current, cause in neighbor systems occur and echo surge current, particularly may be divided into series connection and echo surge current and parallel connection and echo surge current.
The practical recorder data and emulation data of use site, reconstruct BH curve, Fig. 1, figure by voltage and current
2, Fig. 3, Fig. 4 are the BH curve reconstructed under different conditions, and Fig. 6 is practical record when occurring excitation surge current in Operation of Electric Systems
Wave, since excitation surge current caused by the combined floodgate such as transformer on electric loop is superimposed upon being formed on former load current and should gush
There is apparent aperiodic component in stream, electric current, go out the BH curve as shown in Fig. 7 using voltage and current data reconstruction, can from Fig. 7
Changed with finding out that front and back BH curve occurs in excitation surge current.Excitation surge current current recording wave when Fig. 8 is Transformer Close
Shape goes out BH curve as shown in Figure 9 using voltage and current data reconstruction.
By to a large amount of BH curvilinear figure induction and conclusions, there are following features for discovery：
When normal operation and failure, according to load characteristic and fault current size, the BH curve of reconstruct can be with
It for horizontal, vertical, inclined ellipse, or is circle, as shown in Figure 1, Figure 2；Excitation is caused to be gushed when idle-loaded switching-on or bias are run
Stream, BH curvilinear figure is amesiality, such as Fig. 3；When the overexcitation caused by being increased due to voltage, it is special that two-way saturation is presented in BH curve
Sign, such as Fig. 4；From figure 3, it can be seen that the BH curve of reconstruct when excitation surge current has apparent asymmetric feature.
Since transformer has fixed external excitation voltage, due to the symmetry of AC power source, therefore in operating normally
BH curve should be it is symmetrical, symmetrical, electric current and failure when normal operation should be presented in the sampled point in positive-negative half-cycle
Electric current is mainly based on resistive load current, therefore BH curve presents symmetrical, and excitation surge current shoves with overexcitation and has differences, and encourages
BH curve when magnetic shoves is amesiality, and BH curve when overexcitation is shoved is rotational symmetry in first, third quadrant.
Asymmetric feature is presented in the BH curve of excitation surge current, and manual identified is easier, but the only amount of being converted into
Microcomputer based relay protective device could use after the data of change, in order to identify the BH curve asymmetric of excitation surge current shown in Fig. 3
Feature, the present invention use BH curve asymmetry recognition principle shown in fig. 5, by constructing new reference frame, by BH song
Line is divided into four quadrants, from figure 7 it can be seen that the regularity of distribution of BH curve is changed when there is excitation surge current,
The quadrant BH curve having in four quadrants only have it is a bit of passed through even without BH curve, feature accordingly carries out electric system and encourages
The identification that magnetic shoves.Identify whether BH curve has in the distributed number of four quadrant data points according to BH curve to carry out statistics
Asymmetric feature, to identify excitation surge current, specific step is as follows：
High speed digital sample is carried out to voltage, the electric current on an electrical node, the voltage of fluctuation, electric current are converted into characterization
The sample data sequence of its change procedure intercepts voltage, the electricity of the previous complete cycle at this moment according to the sample rate of data
Sample data sequence is flowed, when mains frequency is 50HZ, that is, the sample data sequence of 20ms, voltage data sequence is carried out
The B_one_wave sequence obtained after Integral Processing, as the variation of magnetic induction density B, current data is as H_one_
Wave sequence shows the variation of magnetic field strength H, on two-dimensional surface, H_one_wave sequence is strong as the magnetic field of horizontal direction
The coordinate data of degree H axis, coordinate data of the B_one_wave sequence as the magnetic induction density B axis of vertical direction, use are above-mentioned
Two groups of data sequences construct BH curve shown in fig. 5.Max function can find out the maximum value in specified data sequence, min letter
Number can find out the minimum value in specified data sequence, find out B, H axis direction of this cycle BH curve respectively using max, min
Maximum value minimum, detailed process processing are as follows：
BH curve H axis direction maximum point H_max=max (H_one_wave)；
BH curve H axis direction minimum point H_min=min (H_one_wave)；
BH curve B axle direction maximum point B_max=max (B_one_wave)；
BH curve B axle direction minimum point B_min=min (B_one_wave).
Based on above-mentioned data, in Fig. 5 the coordinate of A, C two o'clock of BH curve be respectively A (H_max, B_max), C (H_min,
B_min), D point coordinate in center shown in Fig. 5 is D（X0, Y0）, wherein X0=(H_max+H_min)/2, Y0 = B_
Max+B_min)/2, using the reference frame that D point is constructed as origin, horizontal axis, the longitudinal axis divide plane where BH curve
For four quadrants.Then distributed number of the data point in four quadrants of reference frame on BH curve is counted respectively, accordingly
Whether identification BH curve has asymmetric feature, to identify whether electric current is excitation surge current.
It is as follows to count distributed number process of the data point on BH curve in four quadrants of reference frame：
The first step：H_one_wave, B_one_wave sequence are carried out to the array H_B_AXIS for being integrated into one two column, often
Corresponding two data of a line respectively indicate the corresponding X of a data point, Y axis coordinate；
Second step：Data scanning is carried out using the coordinate pair coordinate array H_B_AXIS of reference coordinate center D point, and is counted
Meet the quantity of the data point of following rule.
Positioned at reference frame first quartile：X > X0And Y> Y0；
Positioned at the second quadrant of reference frame：X < X0And Y> Y0；
Positioned at reference frame third quadrant：X < X0And Y< Y0；
Positioned at reference frame fourth quadrant：X > X0And Y< Y0；
The counter of four quadrant data points of synchronized update in scanning process：First quartile N1, the second quadrant N2, third as
Limit N3, fourth quadrant N4.
It is as follows that identification excitation surge current method is distributed according to BH curve data point：
If some quadrant does not have BH curve to pass through, excitation surge current can be directly determined as when corresponding sampled point is zero；
If some quadrant has BH curve to pass through, when corresponding sampled point is not zero but numerical value is smaller, need according to first,
Three, two, the distribution comprehensive descision of four-quadrant.I.e. first, third quadrant, second, whether the ratio between the sampled point of fourth quadrant at certain
In a setting range, such as 0.8< N1/N3 <1.2 and 0.8< N2/N4 <Judge between right and wrong excitation surge current when 1.2, otherwise
As excitation surge current.
Recognition methods of the invention is not necessarily to carry out parameter setting and calculating using preceding, the setting work before avoiding use,
It is practical with wide applicability, it can be built in Microcomputer Protection product and be used as protection act criterion.
In order to avoid the false judgment as caused by sampling error under low current, under low current and lower than a certain threshold
When value, do not start above-mentioned recognizer, is used recognition result as the criterion before tripping outlet after Microcomputer Protection starting.
The knowledge of excitation surge current need to only can be realized without increasing any hardware in this recognition methods by the function increase of software
Not, so that the reliable correct movement for protection provides assistant criteria, malfunction, the tripping feelings of protective relaying device are effectively prevented
Condition occurs, and improves the accuracy of protection act, provides a kind of digital criterion for identifying excitation surge current for protective relaying device,
It is easy to program realization.The present invention not only can effectively improve the sensitivity of fault identification, protect the safe and reliable fortune of grid equipment
Row reduces economic loss, while improving the correctness of protection device action, protects the stable operation of electric system.
The above-mentioned processing calculating process for single-phase voltage electric current repeats above-mentioned calculating process i.e. for every phase in three-phase system
It can.
The attached drawing of this specification is used to provide further understanding of the present invention, and is constituted part of this application, the present invention
Illustrative embodiments and their description be used to explain the present invention, do not constitute improper limitations of the present invention.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this field
For art personnel, the invention may be variously modified and varied, done within the spirit and principles of the present invention any to repair
Change, equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (3)
1. a kind of power system excitation inrush current identification method based on reconstruct BH curvilinear characteristic, which is characterized in that an electrical section
Voltage, electric current on point carry out high speed digital sample, and the voltage of fluctuation, electric current are converted to the hits for characterizing its change procedure
According to sequence；It is that magnetic induction is strong by magnetic field strength H axis, vertical direction of horizontal direction by voltage, the combined application of current data
It spends B axle and reconstructs BH curve；The maximum point A (H_max, B_max) of B axle on BH curve, H axis direction, minimum point are found out respectively
C (H_min, B_min) and new center D ((H_max+H_min)/2, (B_max+B_min)/2) point；With
New center D point is that origin constructs reference frame, and plane where BH curve is divided into four by horizontal axis, the longitudinal axis in reference frame
A quadrant；Then distributed number of the data point in four quadrants of reference frame on BH curve is counted respectively, is identified accordingly
The graphic feature of BH curve, to identify whether electric current is excitation surge current.
2. the power system excitation inrush current identification method as described in claim 1 based on reconstruct BH curvilinear characteristic, feature exist
In counting distributed number of the data point in four quadrants of reference frame on BH curve, identify the figure of BH curve accordingly
Feature, to identify that the step of whether electric current is excitation surge current is as follows：
The first step：H_one_wave, B_one_wave sequence are carried out to the array H_B_AXIS for being integrated into one two column, every a line
Corresponding two data respectively indicate the corresponding X of a data point, Y axis coordinate；
Second step：Data scanning is carried out using the coordinate pair coordinate array H_B_AXIS of reference coordinate center D point, and counts and meets
The quantity of the data point of following rule；
Positioned at reference frame first quartile：X > X0 And Y> Y0；
Positioned at the second quadrant of reference frame：X < X0 And Y> Y0；
Positioned at reference frame third quadrant：X < X0 And Y< Y0；
Positioned at reference frame fourth quadrant：X > X0 And Y< Y0；
The X0=(H_max+H_min)/2, Y0= (B_max + B_min) / 2；
The counter of four quadrant data points of synchronized update in scanning process：First quartile N1, the second quadrant N2, third quadrant
N3, fourth quadrant N4；
Third step：According to following feature, according to distributed number of the data point on BH curve in four quadrants of reference frame
To identify excitation surge current；
If some quadrant does not have BH curve to pass through, excitation surge current can be directly determined as when corresponding data point is zero；
If some quadrant has BH curve to pass through, when corresponding data point is not zero but numerical value is smaller, need according to first and third,
Two, the distribution comprehensive descision of four-quadrant, i.e., first, third quadrant, second, whether the ratio between the data point of fourth quadrant set at some
Determine in range, such as m1< N1/N3 <M2 and m1< N2/N4 <Judge between right and wrong excitation surge current when m2, otherwise as excitation
It shoves.
3. the power system excitation inrush current identification method as claimed in claim 2 based on reconstruct BH curvilinear characteristic, feature exist
In taking m1=0.8, m2=1.2.
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| CN110504658B (en) * | 2019-07-15 | 2021-05-04 | 三峡大学 | Transformer differential protection method based on two-dimensional space reconstruction current characteristic track |
| CN112564039B (en) * | 2020-11-25 | 2023-05-12 | 国能神福(石狮)发电有限公司 | Adaptive transformer inrush current suppression method |
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| CN105137166B (en) * | 2015-09-09 | 2017-11-28 | 乐晓蓉 | Power system excitation inrush current identification method |
| CN105223450B (en) * | 2015-11-02 | 2018-06-26 | 乐晓蓉 | Transformer core state on_line monitoring method |
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