CN109802370A - A kind of T-type line differential protection improvement criterion - Google Patents
A kind of T-type line differential protection improvement criterion Download PDFInfo
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Abstract
A kind of T-type line differential protection of the present invention improves criterion, it specifically carries out in accordance with the following steps: using outside the monophase field double line terminal R-L, troubles inside the sample space component Model, in conjunction with longitudinal impedance outside double line terminal area, different fault signature when troubles inside the sample space, it obtains protection of the double line terminal on R-L uniline and improves criterion, T-type line is obtained on R-L uniline outside generating region further according to similitude, protection when protection when troubles inside the sample space improves criterion and T-type line generation troubles inside the sample space when the protection after three-phase line decoupling improves criterion and external area error occurs for T-type line after three-phase line decouples improves criterion.The problem of a kind of T-type line differential protection of the present invention improves criterion realization and overcomes conventional current differential protection adjusting difficulty, is saturated vulnerable to capacitance current and current transformer transient state.
Description
Technical field
The invention belongs to transmission line of alternation current technical field of relay protection, and in particular to a kind of T-type line differential protection changes
Into criterion.
Background technique
With the access of large-scale distributed power supply, distributed power plant (including wind power plant) interconnection of T-type or multiterminal is got over
Appeared in power grid frame structure more so that the method for operation of network system is increasingly complex, cause routinely system match
The relay protection set faces huge challenge.Therefore, the reliability, selective, sensitive protected after multiterminal transmission line malfunction is studied
Property has a very important significance.
Currently, T-type or multiterminal transmission line of electricity mostly use current differential protection as main relaying configuration.According to differential guarantor
The form of the composition of difference current and stalling current is different in shield, and Protection criteria is broadly divided into that total current phasor is differential, various shapes
The different forms such as the current failure component of formula is differential, zero sequence current differential protection, sampling value difference, current phase are differential, so different
The sensitivity of form criterion and reliability be not also identical.In long range ultra-high-tension power transmission line, due to depositing for capacitance current
Out-of-balance current is being caused to increase, it is possible to cause the malfunction of current differential protection.Currently, main act threshold by raising
Value or the method for condenser current compensation adversely affect to make up capacitance current to differential protection bring.But improve current differential
The restraint coefficient and starting threshold value of protection, will certainly weaken the sensitivity of protection, and various compensation methodes have its own
The shortcomings that.Due to the particularity of multi-point circuit itself, short circuit current is the sum of each end electric current when external area error, and amplitude is very big,
It is easy to be saturated the current transformer at nearly failure end, to cause the malfunction of differential protection.Identify electric current both at home and abroad at present
The method of mutual inductor saturation has time difference method, harmonic restraint method, Wavelet Detection method calculus of finite differences etc., but above-mentioned various methods have centainly
The shortcomings that.
Summary of the invention
The purpose of the present invention is to provide a kind of T-type line differential protections to improve criterion, realizes T-type ultra-high-tension power transmission line
After breaking down can accurate, sensitive Judging fault and effective action, it is difficult to overcome the adjusting of conventional current differential protection, vulnerable to
The problem of capacitance current and current transformer transient state are saturated.
The technical scheme adopted by the invention is that a kind of T-type line differential protection improves criterion, specifically according to the following steps
Implement:
Step 1: using outside the monophase field double line terminal R-L, troubles inside the sample space component Model, in conjunction with longitudinal impedance in double line terminal
Fault signature outside area, different when troubles inside the sample space obtains protection of the double line terminal on R-L uniline and improves criterion；
Step 2: using outside the monophase field T-type line R-L, troubles inside the sample space component Model, improved in conjunction with the protection that step 1 obtains
Criterion, according to similitude, obtain T-type line on R-L uniline outside generating region, troubles inside the sample space when protection improve criterion；
Step 3: T-type line three-phase fault complementary network figure is used, in conjunction with event in the generating region of T-type line one end in step 2
When barrier, the relational expression of the power-frequency voltage fault component difference at the other both ends of T-type line, according to similitude, analysis obtains T-type line hair
Protection when raw troubles inside the sample space after three-phase line decoupling improves criterion, and the T-type line obtained in conjunction with step 2 is in R-L phase line
Protection when external area error occurs for road improves criterion, according to similitude, obtains when external area error occurs for T-type line in triple line
Protection after the decoupling of road improves criterion.
The features of the present invention also characterized in that
Step 1 is specific as follows:
The both ends setting of the double line terminal outside the monophase field double line terminal R-L, in troubles inside the sample space component Model is electrical respectively
The end measurement end m and the end n, different fault signature when in conjunction with longitudinal impedance outside double line terminal area, troubles inside the sample space is, it is specified that each end electricity
The positive direction of stream is the direction that bus flows to protected circuit, show that protection improvement of the double line terminal on R-L uniline is sentenced
According to shown in such as formula (1), the formula (1) are as follows:
In formula (1),WithIt is the power current fault component at the end double line terminal m Yu the end n respectively,For the end m with
The power current fault component at the end n and,It is poor for the end double line terminal m and the voltage failure component at the end n, WithIt is the power-frequency voltage fault component at the end double line terminal m Yu the end n respectively, z is single
The line impedance of bit length, D are protected circuit overall lengths,
Wherein,The event outside generating region on R-L uniline for double line terminal
Protection when barrier improves criterion,For double line terminal on R-L uniline generating region
Protection when internal fault improves criterion,It is double line terminal in R-L
Protection on uniline outside generating region, when internal fault improves the actuating quantity of criterion,It is line impedance.
Step 2 is specifically implemented according to the following steps:
Step 2.1: the double line terminal obtained according to step 1 improves double in criterion (1) in the protection on R-L uniline
Protection of the end line when external area error occurs on R-L uniline improves the form of actuating quantity and line impedance in criterion,
According to similitude, analyzes protection of the T-type line when external area error occurs on R-L uniline and improves criterion:
A T node is set on the T node in T-type line outside the monophase field T-type line R-L in fault component model to survey
End is measured, sets three electric measurement end m on three ends in T-type line outside the monophase field T-type line R-L in fault component model
End, the end n, the end p, when external area error occurs for the end T-type line m, power-frequency voltage fault component difference such as formula (2) institute at the end m and the end n
Show, the formula (2) are as follows:
In formula,WithIt is the power-frequency voltage fault component at the end T-type line m, the end n respectively,WithIt is T respectively
The power current fault component at the molded line road end m, the end n, z are the line impedance of unit length, D1、D2Respectively T-type line m, n end
The distance of T node is arrived at bus,
Formula (2) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(4), the formula (3), formula (4) are as follows:
In formula (3)It is the power current fault component at the end T-type line p,
The principle being distributed by voltage failure component is higher than when the end T-type line m is mobile to the end n according to the end T-type line m voltage
The relationship of the end n voltage converts formula (4) to formula (5), the formula (5) are as follows:
Inequality (5) conversion is obtained into formula (6) are as follows:
In formula, z (D1+D2) it is the end T-type line m to the route series impedance between the end n,
Similarly, when external area error occurs for the end T-type line m, power-frequency voltage fault component difference between the end m and the end p is obtained
Relational expression (7) are as follows:
In formula (7),It is the power-frequency voltage fault component at the end T-type line p, D3It is T-type line p end bus to T node
Distance,
Formula (7) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(8), the formula (8) are as follows:
The principle being distributed by voltage failure component, when the end T-type line m is mobile to the end p, T-type line m end voltage is higher than the end p
The relationship of voltage converts formula (8) to formula (9), the formula (9) are as follows:
Inequality (9) abbreviation is obtained into formula (10) are as follows:
In formula (10), z (D1+D3) it is the end T-type line m to the route series impedance between the end p,
Similarly, when external area error occurs for the end T-type line m, power-frequency voltage fault component difference between the end n and the end p is obtained
Relational expression (11) are as follows:
In formula (11),It is the power-frequency voltage fault component at the end T-type line n, D2It is T-type line n end bus to T node
Distance,
Formula (11) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(12), the formula (12) are as follows:
The principle being distributed by voltage failure component, when the end T-type line n is mobile to the end p, T-type line n end voltage is higher than the end p
The relationship of voltage converts formula (12) to formula (13), the formula (13) are as follows:
Inequality (13) conversion is obtained into formula (14) are as follows:
In formula (14), z (D2+D3) it is the end T-type line n to the route series impedance between the end p,
As the reference voltage with fault point voltage, according to voltage distribution principle, voltage difference amplitude between both ends is selected
In maximum oneAs the voltage difference in setting valve, it is expressed as formula (15):
Convolution (6), (10), (14) and formula (11) show that T-type line is in R- when external area error occurs for the end T-type line m
Protection on L uniline improves criterion are as follows:
Wherein,For the actuating quantity of criterion, Z ' is to constituteRoute between both ends
Series impedance, Z '=z (D1+D2) or z (D1+D3) or z (D2+D3),
Similarly, when the end T-type line n, the end p to generation external area error between T node, according to outside the monophase field T-type line R-L
Fault component model obtains the identical protection with formula (16) and improves criterion, therefore formula (16) is that T-type line is sent out on R-L uniline
Protection when raw external area error improves criterion；
Step 2.2: the double line terminal obtained according to step 1 on R-L uniline outside generating region, troubles inside the sample space when guarantor
Shield improves the form of actuating quantity in criterion (1), line impedance, according to similitude, analyzes T-type line troubles inside the sample space:
A T node is set on the T node in the T-type line in the single-phase troubles inside the sample space component Model of T-type line R-L to survey
End is measured, sets three electric measurement end m on three ends in T-type line outside the monophase field T-type line R-L in fault component model
End, the end n, the end p, when troubles inside the sample space occurs for the end T-type line m, the phasor and expression of three end power current fault component of T-type line
Are as follows:
In formulaIt is the equivalent power frequency fault current of fault point,
The power-frequency voltage fault component difference at T-type line m, n both ends indicates are as follows:
D is length of the fault point to the end m in formula (13),
Convolution (17), (18) obtain power-frequency voltage fault component difference relational expression such as formula (19) institute at T-type line m, n both ends
Show:
In formula (19),
Conversion type (19) obtains formula (20):
When troubles inside the sample space occurs according to route, the power-frequency voltage fault component amplitude at measurement of correlation end can be with failure point
Set separate and the relationship being gradually reduced, obtain formula (21):
In formula (21),For the practical power-frequency voltage in fault point,
Convolution (20) and formula (21) show that T-type line is in R-L phase line when troubles inside the sample space occurs for the end T-type line m
The protection of road improves criterion are as follows:
Wherein,For the actuating quantity for improving criterion, Z ' is to constituteBoth ends it
Between route series impedance, Z '=z (D1+D2) or z (D1+D3),
Similarly, when troubles inside the sample space occurs for the end T-type line n, the end p, according to the single-phase troubles inside the sample space component mould of T-type line R-L
Type obtains the identical protection with formula (22) and improves criterion, therefore formula (22) is that on R-L uniline troubles inside the sample space occurs for T-type line
When protection improve criterion,
To sum up, T-type line on R-L uniline outside generating region, troubles inside the sample space when protection improve criterion are as follows:
Detailed process is as follows for step 3:
Step 3.1: a T is set on the T node in the T-type line in T-type line three-phase fault complementary network model
Node measurement end sets three electric measurements on three ends in the T-type line in T-type line three-phase fault complementary network model
The end m, the end n, the end p are held, when troubles inside the sample space occurs for the end m, the power-frequency voltage fault component difference at the both ends m, n is indicated are as follows:
In formula (24),The power-frequency voltage fault component at T-type line m, n both ends is represented,It is the power frequency zero-sequence current fault component at the end T-type line m, the end n, the end p respectively,It is the power frequency zero-sequence current failure of the end T-type line m, the end n, the end p after zero sequence compensation point respectively
Amount,Pass through the modified fault component of zero sequence for the end T-type line n,It is the end T-type line m, the end n, the end p respectively
Power frequency zero-sequence current, zmm、zm1It is the mutual impedance at the end m to unit length route between T node, positive sequence impedance, z respectivelynm、zn1
It is the mutual impedance at the end n to unit length route between T node, positive sequence impedance, D respectively1、D2Respectively T-type line m, n end bus
Locate the distance to T node, d is length of the fault point to the end m；Wherein,Expression formula beK1、K2For zero sequence current compensation factor, zn0For the end n
To the zero sequence impedance of unit length route between T node,
According to the relational expression (25) of the residual voltage of T-type line and zero-sequence current:
In formula (25),The respectively power frequency residual voltage at the end T-type line m, the end n, zm0For the end m to T node it
Between unit length route zero sequence impedance, zn0For the end n to the zero sequence impedance of unit length route between T node,
Formula (25) are substituted into formula (24), to the zero-sequence current continuous item in formula (24)It is replaced, replaces deformed expression formula are as follows:
Work as zmm/zn0Ratio be 0.3 when, then have zmmzn0-znmzm0=0, this up-to-date style (26) indicates are as follows:
In formula (27),It is obtained after being corrected respectively under three-phase line by route both ends residual voltage
The end m, the end n voltage failure component,
Work as zmm/zn0Ratio be not equal to 0.3, i.e. zmmzn0-znmzm0When ≠ 0, obtained using weighted mean method:
In formula (28),For be weighted under the three-phase line that the method for average obtains decouple after the end m fault component, To be weighted the three-phase line that the method for average obtains
The end n voltage failure component after lower decoupling,
Expression formula (28) when troubles inside the sample space occurs according to T-type line after three-phase decouples and the T-type as obtained in step 2
Formula (18) when troubles inside the sample space occurs for route under uniline has similitude, deforms to obtain following relational expression by decoupling:
When according to troubles inside the sample space occurs, the voltage failure component amplitude at measurement of correlation end can be separate with position of failure point
And be gradually reduced, therefore obtain the maximum voltage fault component difference expression formula of T-type line any two ends are as follows:
Convolution (29) and formula (30) obtain the end T-type line m to event in generating region when generation troubles inside the sample space between T node
When barrier, the protection after three-phase line decoupling improves criterion are as follows:
In formula (31),Poor for the maximum voltage fault component of T-type line any two ends, Z " is the end T-type line m, n
Route positive sequence series impedance corresponding to the maximum voltage fault component difference of any two ends, footmark in end, p end lineFor phase
Sequence；WhereinZ "=z (D1+D2) or z (D1+D3) or z (D2+D3),
Similarly, it when troubles inside the sample space occurs for the end T-type line n, the end p, is obtained according to T-type line three-phase fault complementary network model
To protection identical with formula (30) improve criterion, therefore formula (30) be T-type line occur troubles inside the sample space when, three-phase line decoupling after
Protection improve criterion,
It is symmetric line, no Coupling Between Phases, T-type line hair in area when external area error occurs for the T-type line under three-phase line
External area error criterion formula (15) when raw external area error in the case where the protection after three-phase line decoupling improves criterion and T-type line is single-phase
With similitude, obtain:
Protection of the T-type line after three-phase line decoupling can to sum up be obtained and improve criterion are as follows:
The beneficial effects of the present invention are:
1) a kind of T-type line differential protection of the present invention improves criterion, when troubles inside the sample space generation occurs for T-type line, has
Higher sensitivity, when external area error occurs for T-type line, reliability with higher, with different when internal fault external fault
Malfunction will not occur for Protection criteria；
2) a kind of T-type line differential protection of the present invention improves criterion, is decoupled by three-phase line, can eliminate Coupling Between Phases
Influence, may be implemented protection split-phase movement；
3) a kind of T-type line differential protection of the present invention improves criterion, does not include capacitance current in criterion formula, can not be by event
Hinder type, it is full by line capacitance electric current and current transformer transient state to overcome conventional current differential protection for the influence of fault resstance
The problem of being easy to happen malfunction with influence.
Detailed description of the invention
Fig. 1 is that a kind of T-type line differential protection of the present invention improves the single-phase external area error of double line terminal R-L used in criterion
Component Model figure；
Fig. 2 is that a kind of T-type line differential protection of the present invention improves the single-phase troubles inside the sample space of double line terminal R-L used in criterion
Component Model figure；
Fig. 3 is that a kind of T-type line differential protection of the present invention improves the single-phase external area error of T-type line R-L used in criterion
Component Model figure；
Fig. 4 is that a kind of T-type line differential protection improves the single-phase troubles inside the sample space component mould of T-type line R-L used in criterion
Type figure；
Fig. 5 is that a kind of T-type line differential protection of the present invention improves the T-type line three-phase fault complementary network used in criterion
Figure.
Specific embodiment
The present invention is described in detail with concrete principle with reference to the accompanying drawing.
A kind of T-type line differential protection of the present invention improves criterion, the specific steps are as follows:
Step 1: using outside the monophase field double line terminal R-L as shown in Figure 1, 2, troubles inside the sample space component Model, in conjunction with longitudinal direction
Different fault signature when impedance is outside double line terminal area, troubles inside the sample space obtains protection of the double line terminal on R-L uniline
Improve criterion；
Step 2: using outside the monophase field T-type line R-L as shown in Figure 3,4, troubles inside the sample space component Model, in conjunction with step 1
Obtained protection improves criterion, according to similitude, obtain T-type line on R-L uniline outside generating region, troubles inside the sample space when
Protection improves criterion；
Step 3: T-type line three-phase fault complementary network figure is used, in conjunction with event in the generating region of T-type line one end in step 2
When barrier, the relational expression of the power-frequency voltage fault component difference at the other both ends of T-type line, according to similitude, analysis obtains T-type line hair
Protection when raw troubles inside the sample space after three-phase line decoupling improves criterion, according to similitude, obtains T-type line and external area error occurs
When three-phase line decoupling after protection improve criterion.
Step 1 is specific as follows:
As shown in Figure 1, 2, double line terminal outside the monophase field double line terminal R-L, in troubles inside the sample space component Model respectively
Both ends set the electric measurement end end m and the end n, and each positive direction for holding electric current is the direction that bus flows to protected circuit,WithIt is the power current fault component at the end double line terminal m Yu the end n respectively,For the power current fault component at the end m and the end n
With,It is poor for the end double line terminal m and the voltage failure component at the end n, WithPoint
It is not the power-frequency voltage fault component at the end double line terminal m Yu the end n, z is the line impedance of unit length, and D is that protected circuit is complete
It is long, ZmAnd ZnIt is the equivalent system impedance that route is respectively held, R respectivelyFIt is fault resstance,WithIt is the equivalent power frequency electric in fault point
Kinetic potential and fault current,It is the practical power-frequency voltage value on the route of fault point,
According to the statement of longitudinal impedance:
Different fault signature when in conjunction with longitudinal impedance outside double line terminal area, troubles inside the sample space:
When | Δ Zop| > | zD | when, external area error occurs for route；When | Δ Zop| < | zD | when, troubles inside the sample space occurs for route,
Show that protection of the double line terminal on R-L uniline improves shown in criterion such as formula (1), the formula (1) are as follows:
In formula (1), whereinIt is sent out on R-L uniline for double line terminal
Protection when raw external area error improves criterion,It is double line terminal in R-L uniline
Protection when upper generation troubles inside the sample space improves criterion,For both-end
Route on R-L uniline outside generating region, internal fault when protection improve the actuating quantity of criterion,It is line impedance.
The improvement criterion description of differential protection at this time are as follows: by comparing route both ends current failure component vector and and both ends
Voltage failure component difference judges area's internal and external fault of route than the size relation of upper line impedance.WhereinWithAn electrical triangle equilibrium relation will be constituted, when external area error occurs,WithThe difference of electric current phasor
Amplitude be significantly less thanAmplitude, according to Triangle Principle, the difference on both sides is less than third side, it is ensured that former in the area outside
The reliability of innovatory algorithm when barrier.Similarly, when troubles inside the sample space occurs,WithThe sum of electric current phasor amplitude it is bright
It is aobvious to be greater thanAmplitude, the sum of both sides of triangle be greater than third side, it is ensured that innovatory algorithm can when troubles inside the sample space
By property.
Step 2 is specifically implemented according to the following steps:
Step 2.1: the double line terminal obtained according to step 1 improves double in criterion (1) in the protection on R-L uniline
Protection of the end line when external area error occurs on R-L uniline improves the form of actuating quantity and line impedance in criterion,
According to similitude, analyzes protection of the T-type line when external area error occurs on R-L uniline and improves criterion:
As shown in figure 3, being set on T node in T-type line outside the monophase field T-type line R-L in fault component model
One T node measurement end sets three on three ends in T-type line outside the monophase field T-type line R-L in fault component model
The electric measurement end end m, the end n, the end p, when external area error occurs for the end T-type line m, the end m and the power-frequency voltage fault component at the end n are poor
As shown in formula (2), the formula (2) are as follows:
In formula,WithIt is the power-frequency voltage fault component at the end T-type line m, the end n respectively,WithIt is respectively
The power current fault component at the end T-type line m, the end n, z are the line impedance of unit length, D1、D2Respectively T-type line m, n end
The distance of T node is arrived at bus,
Formula (2) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(4), the formula (3), formula (4) are as follows:
In formula (3)It is the power current fault component at the end T-type line p,
The principle being distributed by voltage failure component is higher than when the end T-type line m is mobile to the end n according to the end T-type line m voltage
The relationship of the end n voltage converts formula (4) to formula (5), the formula (5) are as follows:
It here is since with the voltage failure component of fault point, for reference, the voltage of fault point is voltage failure component at this time
Maximum value, the voltage failure component from the end m to the end n are gradually reduced with the separate of fault point, and a monotone decreasing is presented
Trend, its voltage failure component is substantially zeroed when arriving the end n, so the voltage failure component difference at the end m to n end line both ends is whole section
Pressure drop on route.
Inequality (5) conversion is obtained into formula (6) are as follows:
In formula, z (D1+D2) it is the end T-type line m to the route series impedance between the end n,
Similarly, when external area error occurs for the end T-type line m, power-frequency voltage fault component difference between the end m and the end p is obtained
Relational expression (7) are as follows:
In formula (7),It is the power-frequency voltage fault component at the end T-type line p, D3It is T-type line p end bus to T node
Distance,
Formula (7) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(8), the formula (8) are as follows:
The principle being distributed by voltage failure component, when the end T-type line m is mobile to the end p, T-type line m end voltage is higher than the end p
The relationship of voltage converts formula (8) to formula (9), the formula (9) are as follows:
Inequality (9) abbreviation is obtained into formula (10) are as follows:
In formula (10), z (D1+D3) it is the end T-type line m to the route series impedance between the end p,
By formula (10) it is found that when the end T-type line m occur external area error when, the end m, the end n voltage failure component voltage difference with
The end m to n end line series impedance ratio be greater than each end current failure component phasor and, form is identical with formula (1), with bright
Aobvious external area error characteristic.
Similarly, when external area error occurs for the end T-type line m, power-frequency voltage fault component difference between the end n and the end p is obtained
Relational expression (11) are as follows:
In formula (11),It is the power-frequency voltage fault component at the end T-type line n, D2It is T-type line n end bus to T node
Distance,
Formula (11) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(12), the formula (12) are as follows:
The principle being distributed by voltage failure component, when the end T-type line n is mobile to the end p, T-type line n end voltage is higher than the end p
The relationship of voltage converts formula (12) to formula (13), the formula (13) are as follows:
Inequality (13) conversion is obtained into formula (14) are as follows:
In formula (14), z (D2+D3) it is the end T-type line n to the route series impedance between the end p,
By formula (14) it is found that when external area error occurs for the end T-type line m, the end m to the end m to the phase of p end line both end voltage
The ratio between corresponding route series impedance of amount difference is greater than three end electric current phasors and form is identical as formula (1), has apparent area
Outer fault characteristic.
As the reference voltage with fault point voltage, according to voltage distribution principle, the end n to the end T and the end p to the electricity between the end T
Pressure difference can be described as the product of each impedance and its respective current failure component, therefore the voltage failure at the end n to the end p divides
Amount difference can be obtained by the sum of above-mentioned two sections of voltage differences.Again because the voltage failure component of T node is that the end n is powered on to p end line
Press fault component it is more maximum, the end n, the end p both ends voltage failure component list is respectively presented along route with a distance from T node
The relationship that tune successively decreases, and the relationship that the sum of actually this two sections of voltage failure component differences is subtracted each other for the two compare the end m, p and m, n
The voltage failure component at end is poor, takes the ratio of the corresponding series impedance of the voltage difference at the both ends n, p as setting valve, protection becomes
It is unreliable, so that braking amount is become smaller, be easy to cause the malfunction of protection.And the end route m is to the both end voltage at the end n, the end m to the end p
Fault component difference is reflected as the sum of two-termial line pressure drop, and one surely obtains the voltage difference as long as having current failure component, and m is arrived at end
The end n, the value of the end m to the end p voltage difference are all stable, reliable.Although wherein using the end m to the end n, the end m to the end p voltage difference as setting valve
In voltage difference all have certain reliability, but in order to make innovatory algorithm in T-type line protection with more reliability, choosing
It is extremely important to select between both ends in the amplitude of voltage difference maximum one, therefore as the reference voltage with fault point voltage, according to electricity
Distribution principle is pressed, voltage difference amplitude between both ends is selectedIn maximum oneAs the voltage in setting valve
Difference is expressed as formula (15):
Again because the difference of n, p both end voltage fault component is possible to be zero, only need to analyzeThe size of value,
Convolution (6), (10), (14) and formula (11) show that T-type line is in R- when external area error occurs for the end T-type line m
Protection on L uniline improves criterion are as follows:
Wherein,For the actuating quantity of criterion, Z ' is to constituteRoute between both ends
Series impedance, Z '=z (D1+D2) or z (D1+D3) or z (D2+D3),
Similarly, when the end T-type line n, the end p to generation external area error between T node, according to outside the monophase field T-type line R-L
Fault component model obtains the identical protection with formula (16) and improves criterion, therefore formula (16) is that T-type line is sent out on R-L uniline
Protection when raw external area error improves criterion,
Due to working as D for the end n, the end p2=D3When, Zns、ZpsThe bigger one end of middle system impedance, the corresponding end
False voltage component at bus is bigger, so that the pressure of the voltage failure component on failure end to this big end line of system impedance
Drop it is smaller, that is, the end false voltage component withDifference amplitude with regard to smaller, to obtainWork as Zns
=ZpsWhen, D2、D3The longer one end of middle route, the false voltage component at the corresponding end bus is smaller, so that failure end
The pressure drop of false voltage component on this end line big to system impedance is bigger, that is, the end false voltage component withDifference modulus value it is bigger, to obtain
When external area error occurs, due to the amplitude very little of three end current failure component vector sums, it is close to zero, and setting valve
For the amplitude for the route series impedance ratio that maximum voltage fault component difference is connected with its both ends, it ensure that actuating quantity is less than adjusting
Value improves the reliable of differential relaying algorithm to ensure that；
Step 2.2: the double line terminal obtained according to step 1 on R-L uniline outside generating region, troubles inside the sample space when guarantor
Shield improves the form of actuating quantity in criterion (1), line impedance, according to similitude, analyzes T-type line troubles inside the sample space:
As shown in figure 4, being set on the T node in the T-type line in the single-phase troubles inside the sample space component Model of T-type line R-L
One T node measurement end sets three on three ends in T-type line outside the monophase field T-type line R-L in fault component model
The electric measurement end end m, the end n, the end p, when troubles inside the sample space occurs for the end T-type line m, three end power current fault component of T-type line
Phasor and expression are as follows:
In formulaIt is the equivalent power frequency fault current of fault point,
The power-frequency voltage fault component difference at T-type line m, n both ends indicates are as follows:
D is length of the fault point to the end m in formula (13),
Convolution (17), (18) obtain power-frequency voltage fault component difference relational expression such as formula (19) institute at T-type line m, n both ends
Show:
In formula (19),
Conversion type (19) obtains formula (20):
When troubles inside the sample space occurs according to route, the power-frequency voltage fault component amplitude at measurement of correlation end can be with failure point
Set separate and the relationship being gradually reduced, obtain formula (21):
In formula (21),For the practical power-frequency voltage in fault point,
Convolution (20) and formula (21) show that T-type line is in R-L phase line when troubles inside the sample space occurs for the end T-type line m
The protection of road improves criterion are as follows:
Wherein,For the actuating quantity for improving criterion, Z ' is to constituteBoth ends
Between route series impedance, Z '=z (D1+D2) or z (D1+D3),
Each measurement end voltage failure component and line length and system impedance are in a linear relationship, and any two ends are maximum in three ends
Voltage failure component difference deterministic process with occur external area error when discuss the method for the relationship of the two it is consistent, to obtain
It is each holding current failure component and be significantly greater than when troubles inside the sample space occurs for routeWith bright
Aobvious troubles inside the sample space characteristic,
Similarly, when troubles inside the sample space occurs for the end T-type line n, the end p, according to the single-phase troubles inside the sample space component mould of T-type line R-L
Type obtains the identical protection with formula (22) and improves criterion, therefore formula (22) is that on R-L uniline troubles inside the sample space occurs for T-type line
When protection improve criterion,
To sum up, T-type line on R-L uniline outside generating region, troubles inside the sample space when protection improve criterion are as follows:
Detailed process is as follows for step 3:
Step 3.1: as shown in figure 5, the T in Fig. 5 in the T-type line in T-type line three-phase fault complementary network model
A T node measurement end is set on node, on three ends in the T-type line in T-type line three-phase fault complementary network model
Three electric measurement ends end m, the end n, the end p are set, the positive direction of each current failure component marks on the diagram respectively, Zsm、Zsn,
Zsp, Zmm、Zmn、Zmp, Z1m、Z1n、Z1pIt is the system self-impedance that T-type line is respectively held respectively, system mutual impedance, system positive sequence impedance,
zms、zmm、zm1、zns、znm、zn1、zps、zpm、zp1The end m to the end T respectively, the end n to the end T, the end p to the end T unit length route from
Impedance, mutual impedance, positive sequence impedance, RFIt is the fault resstance in three-phase line model and zero sequence equivalent circuit model, It is each phase power frequency in three end of route respectively
Voltage failure component； It is that three end of route is each respectively
Phase power current fault component,
When troubles inside the sample space occurs for the end m, the power-frequency voltage fault component difference at the both ends m, n is indicated are as follows:
In formula (24),The power-frequency voltage fault component at T-type line m, n both ends is represented,It is the power frequency zero-sequence current fault component at the end T-type line m, the end n, the end p respectively,It is the power frequency zero-sequence current failure of the end T-type line m, the end n, the end p after zero sequence compensation point respectively
Amount,Pass through the modified fault component of zero sequence for the end T-type line n,It is the end T-type line m, the end n, the end p respectively
Power frequency zero-sequence current, D1、D2The distance of T node is arrived respectively at the bus of T-type line m, n end, d is length of the fault point to the end m
Degree；Wherein,Expression formula beK1、K2For zero-sequence current
Penalty coefficient, zn0For the end n to the zero sequence impedance of unit length route between T node,
According to the relational expression (25) of the residual voltage of T-type line and zero-sequence current:
In formula (25),The respectively power frequency residual voltage at the end T-type line m, the end n, zm0For the end m to T node
Between unit length route zero sequence impedance, zn0For the end n to the zero sequence impedance of unit length route between T node,
Due to generating Coupling Between Phases when unbalanced fault occurs for three-phase line, formula (25) are substituted into formula (24), to formula
(24) the zero-sequence current continuous item inIt is replaced, replaces
Deformed expression formula are as follows:
Work as zmm/zn0Ratio be 0.3 when, then have zmmzn0-znmzm0=0, this up-to-date style (26) can indicate are as follows:
In formula (27),It is obtained after being corrected respectively under three-phase line by route both ends residual voltage
The end m, the end n voltage failure component,
Work as zmm/zn0Ratio be not equal to 0.3, i.e. zmmzn0-znmzm0When ≠ 0, obtained using weighted mean method:
In formula (28),For the end the m voltage failure being weighted after being decoupled under the three-phase line that the method for average obtains
Component, For be weighted that the method for average obtains three
The end n voltage failure component after being decoupled under phase line,
Expression formula (28) when troubles inside the sample space occurs according to T-type line after three-phase decouples and the T-type as obtained in step 2
Formula (18) when troubles inside the sample space occurs for route under uniline has similitude, deforms to obtain following relational expression by decoupling:
When according to troubles inside the sample space occurs, the voltage failure component amplitude at measurement of correlation end can be separate with position of failure point
And be gradually reduced, therefore obtain the maximum voltage fault component difference expression formula of T-type line any two ends are as follows:
Convolution (29) and formula (30) obtain the end T-type line m to event in generating region when generation troubles inside the sample space between T node
When barrier, the protection after three-phase line decoupling improves criterion are as follows:
In formula (31),Poor for the maximum voltage fault component of T-type line any two ends, Z " is the end T-type line m, n
Route positive sequence series impedance corresponding to the maximum voltage fault component difference of any two ends, footmark in end, p end lineFor phase
Sequence；WhereinZ "=z (D1+D2) or z (D1+D3) or z (D2+D3),
Similarly, it when troubles inside the sample space occurs for the end T-type line n, the end p, is obtained according to T-type line three-phase fault complementary network model
To protection identical with formula (30) improve criterion, therefore formula (30) be T-type line occur troubles inside the sample space when, three-phase line decoupling after
Protection improve criterion,
It is symmetric line, no Coupling Between Phases, T-type line hair in area when external area error occurs for the T-type line under three-phase line
External area error criterion formula (15) when raw external area error in the case where the protection after three-phase line decoupling improves criterion and T-type line is single-phase
With similitude, obtain:
Protection of the T-type line after three-phase line decoupling can to sum up be obtained and improve criterion are as follows:
A kind of T-type line differential protection of the present invention improves criterion, show that protection of the double line terminal on R-L uniline changes
Into criterion, T-type line on R-L uniline outside generating region, troubles inside the sample space when protection improve criterion, T-type line in three-phase
Protection after route decoupling improves criterion, is distinguished in the area of route according to triangle equilibrium relation, external area error, wherein nearly event
The fault current of barrier point measurement end is one side of triangle, remaining current failure component respectively held and the Article 2 for triangle
Side, the ratio of the corresponding route series connection positive sequence impedance of any two ends maximum voltage fault component difference is third side in three ends.Work as T
When troubles inside the sample space occurs for molded line road, in three end current failure components and significantly greater than three ends both ends maximum voltage fault component difference and
The ratio of its corresponding route series connection positive sequence impedance, can be described as the sum of both sides of triangle greater than third side, ensure that calculation
The reliability of method；When external area error occurs for T-type line, three end current failure components and it is significantly less than in three ends the maximum electricity in both ends
The ratio for pressing the corresponding route series connection positive sequence impedance of fault component difference can be described as the difference on the both sides of triangle less than the
Three sides ensure that algorithm sensitivity, meanwhile, in criterion formula do not include capacitance current, can not by fault type, fault resstance
It influences, overcome conventional current differential protection is influenced to be easy to happen malfunction by line capacitance electric current and current transformer transient state saturation
The problem of.
The criterion is strictly based on three-phase circuit model, the various malfunctions suitable for T-type line.
Claims (4)
1. a kind of T-type line differential protection improves criterion, which is characterized in that be specifically implemented according to the following steps:
Step 1: using outside the monophase field double line terminal R-L, troubles inside the sample space component Model, in conjunction with longitudinal impedance in double line terminal area
Outside, fault signature different when troubles inside the sample space obtains protection of the double line terminal on R-L uniline and improves criterion；
Step 2: using outside the monophase field T-type line R-L, troubles inside the sample space component Model, sentence in conjunction with the protection improvement that step 1 obtains
According to, according to similitude, obtain T-type line on R-L uniline outside generating region, troubles inside the sample space when protection improve criterion；
Step 3: T-type line three-phase fault complementary network figure is used, when troubles inside the sample space occurs in conjunction with T-type line one end in step 2,
The relational expression of the power-frequency voltage fault component difference at the other both ends of T-type line, according to similitude, analysis obtains T-type line generating region
Protection when internal fault after three-phase line decoupling improves criterion, and the T-type line obtained in conjunction with step 2 is on R-L uniline
Protection when external area error occurs improves criterion, according to similitude, obtains when external area error occurs for T-type line in three-phase line solution
Protection after coupling improves criterion.
2. a kind of T-type line differential protection according to claim 1 improves criterion, which is characterized in that the step 1 is specific
It is as follows:
The both ends of the double line terminal outside the monophase field double line terminal R-L, in troubles inside the sample space component Model set electric measurement respectively
The end m and the end n are held, different fault signature when in conjunction with longitudinal impedance outside double line terminal area, troubles inside the sample space is, it is specified that respectively hold electric current
Positive direction is the direction that bus flows to protected circuit, show that protection of the double line terminal on R-L uniline improves criterion such as
Shown in formula (1), the formula (1) are as follows:
In formula (1),WithIt is the power current fault component at the end double line terminal m Yu the end n respectively,For the end m and the end n
Power current fault component and,It is poor for the end double line terminal m and the voltage failure component at the end n, WithIt is the power-frequency voltage fault component at the end double line terminal m Yu the end n respectively, z is single
The line impedance of bit length, D are protected circuit overall lengths,
Wherein,It is double line terminal when external area error occurs on R-L uniline
Protection improve criterion,Troubles inside the sample space occurs on R-L uniline for double line terminal
When protection improve criterion,It is double line terminal in R-L phase line
Protection outside the generating region of road, when internal fault improves the actuating quantity of criterion,It is line impedance.
3. a kind of T-type line differential protection according to claim 2 improves criterion, which is characterized in that the step 2 is specific
It follows the steps below to implement:
Step 2.1: the double line terminal obtained according to step 1 improves the both-end line in criterion (1) in the protection on R-L uniline
Protection of the road when external area error occurs on R-L uniline improves the form of actuating quantity and line impedance in criterion, according to
Similitude, protection of the analysis T-type line when external area error occurs on R-L uniline improve criterion:
A T node measurement is set on the T node in T-type line outside the monophase field T-type line R-L in fault component model
It holds, three electric measurement end m is set on three ends in T-type line outside the monophase field T-type line R-L in fault component model
End, the end n, the end p, when external area error occurs for the end T-type line m, power-frequency voltage fault component difference such as formula (2) institute at the end m and the end n
Show, the formula (2) are as follows:
In formula,WithIt is the power-frequency voltage fault component at the end T-type line m, the end n respectively,WithIt is T-type respectively
The power current fault component at the end route m, the end n, z are the line impedance of unit length, D1、D2Respectively T-type line m, n end is female
The distance of T node is arrived at line,
Formula (2) is expressed as formula (4) in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p,
The formula (3), formula (4) are as follows:
In formula (3)It is the power current fault component at the end T-type line p,
The principle being distributed by voltage failure component when the end T-type line m is mobile to the end n, is higher than the end n according to T-type line m end voltage
The relationship of voltage converts formula (4) to formula (5), the formula (5) are as follows:
Inequality (5) conversion is obtained into formula (6) are as follows:
In formula, z (D1+D2) it is the end T-type line m to the route series impedance between the end n,
Similarly, when external area error occurs for the end T-type line m, the relationship of power-frequency voltage fault component difference between the end m and the end p is obtained
Formula (7) are as follows:
In formula (7),It is the power-frequency voltage fault component at the end T-type line p, D3T-type line p end bus to T node away from
From,
Formula (7) is expressed as formula (8) in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p,
The formula (8) are as follows:
The principle being distributed by voltage failure component, when the end T-type line m is mobile to the end p, T-type line m end voltage is higher than the end p voltage
Relationship, convert formula (8) to formula (9), the formula (9) are as follows:
Inequality (9) abbreviation is obtained into formula (10) are as follows:
In formula (10), z (D1+D3) it is the end T-type line m to the route series impedance between the end p,
Similarly, when external area error occurs for the end T-type line m, the relationship of power-frequency voltage fault component difference between the end n and the end p is obtained
Formula (11) are as follows:
In formula (11),It is the power-frequency voltage fault component at the end T-type line n, D2T-type line n end bus to T node away from
From,
Formula (11) is expressed as formula in conjunction with the relational expression (3) of the end T-type line m, the end n, three end power current fault component of the end p
(12), the formula (12) are as follows:
The principle being distributed by voltage failure component, when the end T-type line n is mobile to the end p, T-type line n end voltage is higher than the end p voltage
Relationship, convert formula (12) to formula (13), the formula (13) are as follows:
Inequality (13) conversion is obtained into formula (14) are as follows:
In formula (14), z (D2+D3) it is the end T-type line n to the route series impedance between the end p,
As the reference voltage with fault point voltage, according to voltage distribution principle, voltage difference amplitude between both ends is selectedMiddle maximum
OneAs the voltage difference in setting valve, it is expressed as formula (15):
Convolution (6), (10), (14) and formula (11) show that T-type line is mono- in R-L when external area error occurs for the end T-type line m
Protection on phase line improves criterion are as follows:
Wherein,For the actuating quantity of criterion, Z ' is to constituteRoute between both ends, which is connected, to be hindered
It is anti-, Z '=z (D1+D2) or z (D1+D3) or z (D2+D3),
Similarly, when the end T-type line n, the end p to generation external area error between T node, according to the single-phase external area error of T-type line R-L
Component Model obtains the identical protection with formula (16) and improves criterion, therefore formula (16) is T-type line generating region on R-L uniline
Protection when outer failure improves criterion；
Step 2.2: the double line terminal obtained according to step 1 on R-L uniline outside generating region, troubles inside the sample space when protection change
T-type line troubles inside the sample space is analyzed according to similitude into actuating quantity in criterion (1), the form of line impedance:
A T node measurement is set on the T node in the T-type line in the single-phase troubles inside the sample space component Model of T-type line R-L
It holds, three electric measurement end m is set on three ends in T-type line outside the monophase field T-type line R-L in fault component model
End, the end n, the end p, when troubles inside the sample space occurs for the end T-type line m, the phasor and expression of three end power current fault component of T-type line
Are as follows:
In formulaIt is the equivalent power frequency fault current of fault point,
Shown in the relational expression such as formula (18) of the power-frequency voltage fault component difference at T-type line m, n both ends:
D is length of the fault point to the end m in formula (13),
Convolution (17), (18) obtain shown in the power-frequency voltage fault component difference relational expression such as formula (19) at T-type line m, n both ends:
In formula (19),
Conversion type (19) obtains formula (20):
When troubles inside the sample space occurs according to route, the power-frequency voltage fault component amplitude at measurement of correlation end can be with position of failure point
The separate and relationship that is gradually reduced, obtains formula (21):
In formula (21),For the practical power-frequency voltage in fault point,
Convolution (20) and formula (21) show that T-type line is on R-L uniline when troubles inside the sample space occurs for the end T-type line m
Protection improve criterion are as follows:
Wherein,For the actuating quantity for improving criterion, Z ' is to constituteBetween both ends
Route series impedance, Z '=z (D1+D2) or z (D1+D3),
Similarly, it when troubles inside the sample space occurs for the end T-type line n, the end p, is obtained according to the single-phase troubles inside the sample space component Model of T-type line R-L
Criterion is improved to protection identical with formula (22), therefore formula (22) is T-type line when troubles inside the sample space occurs on R-L uniline
Protection improves criterion,
To sum up, T-type line on R-L uniline outside generating region, troubles inside the sample space when protection improve criterion are as follows:
4. a kind of T-type line differential protection according to claim 3 improves criterion, which is characterized in that the step 3 is specific
Process is as follows:
Step 3.1: a T node is set on the T node in the T-type line in T-type line three-phase fault complementary network model
Measurement end sets three electric measurement end m on three ends in the T-type line in T-type line three-phase fault complementary network model
End, the end n, the end p, when troubles inside the sample space occurs for the end m, the power-frequency voltage fault component difference at the both ends m, n is indicated are as follows:
In formula (24),The power-frequency voltage fault component at T-type line m, n both ends is represented,It is the power frequency zero-sequence current fault component at the end T-type line m, the end n, the end p respectively,It is the power frequency zero-sequence current failure of the end T-type line m, the end n, the end p after zero sequence compensation point respectively
Amount,Pass through the modified fault component of zero sequence for the end T-type line n,It is the end T-type line m, the end n, the end p respectively
Power frequency zero-sequence current, zmm、zm1It is the mutual impedance at the end m to unit length route between T node, positive sequence impedance, z respectivelynm、zn1
It is the mutual impedance at the end n to unit length route between T node, positive sequence impedance, D respectively1、D2Respectively T-type line m, n end bus
Locate the distance to T node, d is length of the fault point to the end m；Wherein,Expression formula beK1、K2For zero sequence current compensation factor, zn0For n
It holds to the zero sequence impedance of unit length route between T node,
According to the relational expression (25) of the residual voltage of T-type line and zero-sequence current:
In formula (25),The respectively power frequency residual voltage at the end T-type line m, the end n, zm0For the end m to list between T node
The zero sequence impedance of bit length route, zn0For the end n to the zero sequence impedance of unit length route between T node,
Formula (25) are substituted into formula (24), to the zero-sequence current continuous item in formula (24)It is replaced, replaces deformed expression formula are as follows:
Work as zmm/zn0Ratio be 0.3 when, then have zmmzn0-znmzm0=0, this up-to-date style (26) indicates are as follows:
In formula (27),The m obtained after being corrected respectively under three-phase line by route both ends residual voltage
End, the end n voltage failure component,
Work as zmm/zn0Ratio be not equal to 0.3, i.e. zmmzn0-znmzm0When ≠ 0, obtained using weighted mean method:
In formula (28),For be weighted under the three-phase line that the method for average obtains decouple after the end m voltage failure component, To be weighted the three-phase that the method for average obtains
The end n voltage failure component after being decoupled under route,
Expression formula (28) when troubles inside the sample space occurs according to T-type line after three-phase decouples and the T-type line as obtained in step 2
Formula (18) when troubles inside the sample space occurs under uniline has similitude, deforms to obtain following relational expression by decoupling:
When according to troubles inside the sample space occurs, the voltage failure component amplitude at measurement of correlation end can with position of failure point far from and by
It is decrescence small, therefore obtain the maximum voltage fault component difference expression formula of T-type line any two ends are as follows:
Convolution (29) and formula (30), obtain the end T-type line m between T node occur troubles inside the sample space when occur troubles inside the sample space when,
Protection after three-phase line decoupling improves criterion are as follows:
In formula (31),Poor for the maximum voltage fault component of T-type line any two ends, Z " is the end T-type line m, the end n, p
Route positive sequence series impedance corresponding to the maximum voltage fault component difference of any two ends, footmark in end lineFor phase sequence；Its
InZ "=z (D1+D2) or z (D1+D3) or z (D2+D3),
Similarly, when troubles inside the sample space occurs for the end T-type line n, the end p, obtained according to T-type line three-phase fault complementary network model and
The identical protection of formula (30) improves criterion, therefore when formula (30) is that troubles inside the sample space occurs for T-type line, the guarantor after three-phase line decoupling
Shield improves criterion,
It is symmetric line, no Coupling Between Phases, T-type line generating region in area when external area error occurs for the T-type line under three-phase line
External area error criterion formula (15) when outer failure in the case where the protection after three-phase line decoupling improves criterion and T-type line is single-phase has
Similitude obtains:
Protection of the T-type line after three-phase line decoupling can to sum up be obtained and improve criterion are as follows:
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| CN112083280A (en) * | 2020-08-27 | 2020-12-15 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Method for identifying fault interval of hybrid multi-terminal direct-current power transmission system |
| CN112083280B (en) * | 2020-08-27 | 2022-07-08 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Method for identifying fault interval of hybrid multi-terminal direct-current power transmission system |
| CN112332371A (en) * | 2020-10-19 | 2021-02-05 | 西安工程大学 | Novel differential protection method of generator based on stator double-layer winding model |
| CN113970686A (en) * | 2021-10-27 | 2022-01-25 | 西南交通大学 | Power distribution network fault detection method and system based on single-ended quantity protection and positioning method |
| CN113970685A (en) * | 2021-10-27 | 2022-01-25 | 西南交通大学 | Power distribution network fault detection method and system based on differential analysis and positioning method |
| CN113970686B (en) * | 2021-10-27 | 2022-08-30 | 西南交通大学 | Power distribution network fault detection method and system based on single-ended quantity protection and positioning method |
| CN113970685B (en) * | 2021-10-27 | 2022-08-30 | 西南交通大学 | Power distribution network fault detection method and system based on differential analysis and positioning method |
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Application publication date: 20190524 |