CN106353641A - Method for discriminating internal and external faults on basis of transverse faults of double-circuit lines of same towers - Google Patents

Abstract

The invention discloses a method for discriminating internal and external faults on the basis of transverse faults of double-circuit lines of the same towers. The method includes steps of 1, judging whether fiber channels are used for pilot distant protection or not, carrying out a step 2 if the fiber channels are used for pilot distant protection or carrying out a step 4 if the fiber channels are not used for pilot distant protection; 2, judging whether bit error rates of the fiber channels are smaller than set values or not, carrying out a step 3 if the bit error rates of the fiber channels are smaller than the set values or carrying out the step 4 if the bit error rates of the fiber channels are not smaller than the set values and are smaller than pilot distant threshold values; 3, acquiring data at two ends of each fiber channel, computing differential flow, discriminating that faults are the internal faults if differential criteria are met by the differential flow and brake currents, or discriminating that the faults are the external faults if the differential criteria are not met by the differential flow and the brake currents; 4, establishing pilot-direction zero-sequence and negative-sequence integration direction criteria; 5, discriminating forward and reverse faults of zero-sequence direction protection; 6, discriminating pilot-direction zero-sequence and negative-sequence integration directions. The method has the advantages that protection misoperation can be effectively prevented, the stability of integral electric power systems can be improved, and safe and stable operation of power grids can be effectively guaranteed.

Description

The method of discrimination of the area's internal and external fault based on multiple-circuit on same tower short circuits

Technical field

The present invention relates to a kind of method of discrimination of the area's internal and external fault based on multiple-circuit on same tower short circuits.

Background technology

Multiple-circuit on same tower, when a loop line occurs disconnection fault, can produce a residual voltage mistake on another loop line Zero point, if by traditional compensation method it may occur that overcompensation, makes originally to be judged to reverse zero sequence direction relay to be judged to Forward direction, with just, leading to, zero sequence is vertical to join malfunction on both sides.

As shown in figure 1, when multiple-circuit on same tower one loop line occurs disconnection fault, being equivalent in the additional net of zero-sequence fault Connect a voltage source in fault point.Now, another loop line perfects circuit and can be made by dual coupling electrically and magnetically simultaneously With the coupling of electricity makes to perfect circuit two ends residual voltage opposite polarity, in such as Fig. 1For positive polarityFor negative polarity, Therefore perfect and a residual voltage zero crossing will be occurred on circuit.

Content of the invention

For the problems referred to above, the present invention provides a kind of sentencing of area's internal and external fault based on multiple-circuit on same tower short circuits , there is the possibility of zero sequence direction malfunction for traditional zero-sequence voltage injection in multiple-circuit on same tower short circuits, put forward in other method The method going out can be effectively prevented the generation of false protection, improves the stability of whole power system, is electricity net safety stable fortune Row provides and preferably ensures.

For realizing above-mentioned technical purpose, reach above-mentioned technique effect, the present invention is achieved through the following technical solutions:

A kind of method of discrimination of the area's internal and external fault based on multiple-circuit on same tower short circuits it is characterised in that include as Lower step:

Step 1, judging that whether longitudinal distance protection adopts optical-fibre channel, if so, then entering step 2, if it is not, then entering step Rapid 4；

Step 2, judge that whether the optical-fibre channel bit error rate is less than setting value, if so, then enter step 3, if it is not, and optical fiber lead to The road bit error rate is less than vertical connection range gate threshold value, then enter step 4；

Step 3, collection optical-fibre channel two end data simultaneously calculate difference stream: when meeting differential criterion, be determined as troubles inside the sample space；When It is unsatisfactory for differential criterion, be determined as external area error；

Step 4, set up pilot direction zero sequence, negative phase-sequence synthesis direction criterion, wherein:

1a) the main criterion of zero sequence direction is:

$|3{\stackrel{\·}{u}}_0-3{\stackrel{\·}{i}}_0{z}_0|>|3{\stackrel{\·}{u}}_0+{\stackrel{\·}{i}}_0{z}_0|---\left(1\right)$

In formula, u₀、i₀For the residual voltage of circuit one end protection device installation place, electric current, its positive direction is all using reference side To,For corresponding residual voltage vector, current phasor, z₀For circuit zero sequence impedance；

1b) the zero-sequence current threshold criterion of zero-sequence voltage injection is:

$\left|3{\stackrel{\·}{i}}_0\right|>300a---\left(3\right)$

2a) negative sequence direction assistant criteria is:

$|3{\stackrel{\·}{u}}_2-3{\stackrel{\·}{i}}_2{z}_2|>|3{\stackrel{\·}{u}}_2+{\stackrel{\·}{i}}_2{z}_2|---\left(4\right)$

In formula, u₂、i₂For the negative sequence voltage of circuit one end protection device installation place, electric current, its positive direction is all using reference side To,For corresponding negative sequence voltage vector, current phasor, z₂For circuit negative sequence impedance；

2b) negative sequence compensation voltage starting criterion is:

$|3{\stackrel{\·}{u}}_2-{\stackrel{\·}{i}}_2{z}_2|>0.02u_n---\left(6\right)$

In formula, u_nFor phase voltage rated value；

2c) negative-sequence current start-up criterion is:

$\left|3{\stackrel{\·}{i}}_2\right|>150a---\left(7\right)$

2d) negative sequence voltage threshold criterion is:

$\left|3{\stackrel{\·}{u}}_2\right|>0.02u_n---\left(8\right)$

Step 5, carry out the forward and reverse fault distinguishing of zero-sequence voltage injection:

When criterion (1), (3) are met with (4), (6), (7) simultaneously, then zero-sequence voltage injection is judged to positive fault；

When criterion (1), (3), (8) satisfaction and (7) are unsatisfactory for, then zero-sequence voltage injection is judged to positive fault；

Step 6, the pilot direction zero sequence that carries out, negative phase-sequence synthesis discriminating direction:

If circuit two ends zero-sequence voltage injection is all judged to positive fault, it is determined as troubles inside the sample space.

Preferably, in step 5, when criterion (1), (4) are unsatisfactory for, and (3), (6), (7) meet, then zero-sequence voltage injection is judged to Reverse fault, otherwise, zero-sequence voltage injection is all judged to fault-free.

The invention has the beneficial effects as follows:

Under the background based on current optical-fibre channel extensive utilization for the method, make full use of optical-fibre channel and can transmit and count in a large number According to characteristic, in the case of being properly received difference stream, using difference stream cog region internal and external fault；Difference stream cannot correctly be obtained Shi Liyong is improved zero, negative sequence direction method of discrimination, solves when common-tower double-return line, a loop line occurs disconnection fault, another One residual voltage zero crossing can be produced on loop line, lead to the problem of zero sequence pilot protection malfunction, the present invention can be effectively prevented The generation of false protection, improves the stability of whole power system.

Brief description

Fig. 1 is zero sequence voltage component distribution schematic diagram during multiple-circuit on same tower open conductors；

Fig. 2 is the flow chart of the method for discrimination based on area's internal and external fault of multiple-circuit on same tower short circuits for the present invention.

Specific embodiment

With specific embodiment, technical solution of the present invention is described in further detail below in conjunction with the accompanying drawings, so that ability The technical staff in domain can be better understood from the present invention and can be practiced, but illustrated embodiment is not as the limit to the present invention Fixed.

A kind of method of discrimination of the area's internal and external fault based on multiple-circuit on same tower short circuits, as shown in Fig. 2 include as Lower step:

Step 1, judging that whether longitudinal distance protection adopts optical-fibre channel, if so, then entering step 2, if it is not, then entering step Rapid 4.

Step 2, judge that whether the optical-fibre channel bit error rate is less than setting value, if so, then enter step 3, if it is not, and optical fiber lead to The road bit error rate is less than vertical connection range gate threshold value, then enter step 4.

Step 3, collection optical-fibre channel two end data simultaneously calculate difference stream: stream of being on duty meets differential criterion with stalling current, sentences Wei not troubles inside the sample space；Otherwise, it is determined as external area error.

Differential criterion is:

$\left\{\begin{array}{c}{i}_{d\mathrm{\φ}}>0.6\×i_{r\mathrm{\φ}}\\ i_{d\mathrm{\φ}}>i_{dset}^h\end{array}\right.$

Wherein: i_dφFor phase difference current, i_dφ=| i_mφ+i_nφ|；i_rφFor phase stalling current, i_rφ=| i_mφ-i_nφ|；For 1.5 times of differential action current ration, i_mφ、i_nφIt is respectively this side, offside split-phase current phasor.

Firstly, for the longitudinal distance protection using optical-fibre channel, increase transmission current-mode analog quantity in optical-fibre channel, when connecing Receiving end judges that the bit error rate of received signal is less than analog quantity threshold value, illustrates that in optical-fibre channel, analog quantity transmission is normal, device can be just Really calculate difference stream thus distinguishing area's internal and external fault using two ends analog data；When longitudinal distance protection adopts non-optical-fibre channel, Or but analog quantity threshold value is more than using optical-fibre channel channel bit error rate but is less than vertical connection range gate threshold value, protection device Using pilot direction zero sequence, negative phase-sequence synthesis discriminating direction area internal and external fault, specific as follows.

Step 4, set up pilot direction zero sequence, negative phase-sequence synthesis direction criterion, wherein:

The criterion of zero-sequence voltage injection is construction in the form of than phase, in improving Protection criteria, in the form of than width The main criterion of zero sequence direction that structural belt compensates:

$|3{\stackrel{\·}{u}}_0-3{\stackrel{\·}{i}}_0{z}_0|>|3{\stackrel{\·}{u}}_0+{\stackrel{\·}{i}}_0{z}_0|---\left(1\right)$

In formula, u₀、i₀For the residual voltage of circuit one end protection device installation place, electric current, its positive direction is all using reference side To,For corresponding residual voltage vector, current phasor, z₀For circuit zero sequence impedance.

Formula (1) to present than width form, its with by 1/3 z₀The residual voltage compensating and the ratio of circuit zero-sequence current composition Phase formula criterion is of equal value:

2/3 z is generally pressed in traditional zero-sequenceprotection₀Carry out residual voltage compensation, in the present invention, compensating impedance is adjusted Whole, it is reduced to 1/3 z₀, another loop line residual voltage overcompensation during can effectively reducing time open conductors of common-tower double-return line Probability.

Meanwhile, for ensureing the effectiveness of the zero sequence measured value participating in calculating, the zero sequence electricity of traditional zero-sequence voltage injection Stream threshold criterion still needs to using (take high resistance earthing fault meter in code and minimum zero sequence):

$\left|3{\stackrel{\·}{i}}_0\right|>300a---\left(3\right)$

For negative phase-sequence criterion, first the negative sequence direction assistant criteria of structural belt compensation:

$|3{\stackrel{\·}{u}}_2-3{\stackrel{\·}{i}}_2{z}_2|>|3{\stackrel{\·}{u}}_2+{\stackrel{\·}{i}}_2{z}_2|---\left(4\right)$

In formula, u₂、i₂For the negative sequence voltage of circuit one end protection device installation place, electric current, its positive direction is all using reference side To,For corresponding negative sequence voltage vector, current phasor, z₂For circuit negative sequence impedance.

In the same manner, this formula with by 1/3 z₂The ratio phase formula criterion of the negative sequence voltage compensating and circuit negative-sequence current composition is of equal value:

The addition of negative sequence direction, is to prevent zero sequence direction from erroneous judgement because of mutual inductance, by 1/3 z₂Compensate it is ensured that Under disconnection fault, perfecting circuit two ends zero-sequence voltage injection at least one end is not in overcompensation, can be judged to reversely, keep away Exempt from protection misoperation.

Construction negative sequence compensation voltage starting criterion:

$|3{\stackrel{\·}{u}}_2-{\stackrel{\·}{i}}_2{z}_2|>0.02u_n---\left(6\right)$

In formula, u_nFor phase voltage rated value；This formula is the offset voltage threshold value that negative sequence direction starts, and is equivalent to by 1/3 z₂The negative sequence voltage amplitude compensating, to ensure the effectiveness of criterion (4).

Construction negative-sequence current start-up criterion is:

$\left|3{\stackrel{\·}{i}}_2\right|>150a---\left(7\right)$

This formula is the electric current threshold value that negative sequence direction starts, the setting same meaning with zero-sequence current threshold.

Construction negative sequence voltage threshold criterion is:

$\left|3{\stackrel{\·}{u}}_2\right|>0.02u_n---\left(8\right)$

This formula is the negative sequence voltage threshold value of identification weak mains, if light current source is unsatisfactory for electric current during line-internal fault Criterion (7), then will certainly meet voltage criterion (8), can arrange, based on this principle, the impact that logic overcomes weak mains to bring.

Step 5, carry out the forward and reverse fault distinguishing of zero-sequence voltage injection:

When criterion (1), (3) are met with (4), (6), (7) simultaneously, then zero-sequence voltage injection is judged to positive fault.

Because negative phase-sequence has light current source problem, in the case of weak mains, there is internal fault, light current source has the high electricity of low current The feature of pressure.Therefore, when criterion (1), (3), (8) satisfaction and (7) are unsatisfactory for, now it is considered weak mains outlet internal fault, Then zero-sequence voltage injection is judged to positive fault.

When criterion (1), (4) are unsatisfactory for, and (3), (6), (7) meet, and now for reverse fault feature, then zero sequence direction is protected Shield is judged to reverse fault.

Otherwise, other situations, zero-sequence voltage injection is all judged to fault-free.

Step 6, the pilot direction zero sequence that carries out, negative phase-sequence synthesis discriminating direction:

If circuit two ends zero-sequence voltage injection is all judged to positive fault, it is determined as troubles inside the sample space, that is, be considered in circuit There is earth fault in portion, protection exit trips.

Otherwise it is assumed that being external area error.

Under the background based on current optical-fibre channel extensive utilization for the method, make full use of optical-fibre channel and can transmit and count in a large number According to characteristic, in the case of being properly received difference stream, using difference stream cog region internal and external fault；Difference stream cannot correctly be obtained Shi Liyong is improved zero, negative sequence direction method of discrimination, solves when common-tower double-return line, a loop line occurs disconnection fault, another One residual voltage zero crossing can be produced on loop line, lead to the problem of zero sequence pilot protection malfunction, the present invention can be effectively prevented The generation of false protection, improves the stability of whole power system.

These are only the preferred embodiments of the present invention, not thereby limit the present invention the scope of the claims, every using this Equivalent structure or equivalent flow conversion that bright description and accompanying drawing content are made, or it is related to be directly or indirectly used in other Technical field, be included within the scope of the present invention.

Claims (3)

1. a kind of method of discrimination of the area's internal and external fault based on multiple-circuit on same tower short circuits is it is characterised in that include as follows Step:

Step 1, judging that whether longitudinal distance protection adopts optical-fibre channel, if so, then entering step 2, if it is not, then entering step 4；

Step 2, judge that whether the optical-fibre channel bit error rate is less than setting value, if so, then enter step 3, if it is not, and optical-fibre channel by mistake Code check is less than vertical connection range gate threshold value, then enter step 4；

Step 3, collection optical-fibre channel two end data simultaneously calculate difference stream: stream of being on duty meets differential criterion with stalling current, is determined as Troubles inside the sample space；Otherwise, it is determined as external area error；

Differential criterion is:

$\left\{\begin{array}{c}{i}_{d\mathrm{\φ}}>0.6\×i_{r\mathrm{\φ}}\\ i_{d\mathrm{\φ}}>i_{dset}^h\end{array}\right.$

Wherein: i_dφFor phase difference current；i_rφFor phase stalling current；For differential action current ration 1.5 times；

Step 4, set up pilot direction zero sequence, negative phase-sequence synthesis direction criterion, wherein:

1a) the main criterion of zero sequence direction is:

$|3{\stackrel{\·}{u}}_0-3{\stackrel{\·}{i}}_0{z}_0|>|3{\stackrel{\·}{u}}_0+{\stackrel{\·}{i}}_0{z}_0|---\left(1\right)$

In formula, u₀、i₀For the residual voltage of circuit one end protection device installation place, electric current, its positive direction all using reference direction,For corresponding residual voltage vector, current phasor, z₀For circuit zero sequence impedance；

1b) the zero-sequence current threshold criterion of zero-sequence voltage injection is:

$\left|3{\stackrel{\·}{i}}_0\right|>300a---\left(3\right)$

2a) negative sequence direction assistant criteria is:

$|3{\stackrel{\·}{u}}_2-3{\stackrel{\·}{i}}_2{z}_2|>|3{\stackrel{\·}{u}}_2+{\stackrel{\·}{i}}_2{z}_2|---\left(4\right)$

In formula, u₂、i₂For the negative sequence voltage of circuit one end protection device installation place, electric current, its positive direction all using reference direction,For corresponding negative sequence voltage vector, current phasor, z₂For circuit negative sequence impedance；

2b) negative sequence compensation voltage starting criterion is:

$|3{\stackrel{\·}{u}}_2-{\stackrel{\·}{i}}_2{z}_2|>0.02u_n---\left(6\right)$

In formula, u_nFor phase voltage rated value；

2c) negative-sequence current start-up criterion is:

$\left|3{\stackrel{\·}{i}}_2\right|>150a---\left(7\right)$

2d) negative sequence voltage threshold criterion is:

$\left|3{\stackrel{\·}{u}}_2\right|>0.02u_n---\left(8\right)$

Step 5, carry out the forward and reverse fault distinguishing of zero-sequence voltage injection:

When criterion (1), (3) are met with (4), (6), (7) simultaneously, then zero-sequence voltage injection is judged to positive fault；

When criterion (1), (3), (8) satisfaction and (7) are unsatisfactory for, then zero-sequence voltage injection is judged to positive fault；

Step 6, the pilot direction zero sequence that carries out, negative phase-sequence synthesis discriminating direction:

If circuit two ends zero-sequence voltage injection is all judged to positive fault, it is determined as troubles inside the sample space.

2. the method for discrimination of a kind of area's internal and external fault based on multiple-circuit on same tower short circuits according to claim 1, It is characterized in that, in step 5, when criterion (1), (4) are unsatisfactory for, and (3), (6), (7) meet, then zero-sequence voltage injection is judged to instead To fault, otherwise, zero-sequence voltage injection is all judged to fault-free.

3. the differentiation side of a kind of area's internal and external fault based on multiple-circuit on same tower short circuits according to claim 1 and 2 Method is it is characterised in that in step 6, remaining situation is all judged to external area error.