CN104578006A - Accident overload blocking method for station territory distance protection section III - Google Patents

Abstract

The invention relates to an accident overload blocking method for a station territory distance protection section III, and belongs to the technical field of protection and control of power systems. The method comprises the following steps: when a grounding fault occurs, overload blocking is released, protection judgment is carried out, a fault line is cut off in combination with main protection, and for an accident overload, blocking protection is carried out to guarantee that a false operation is not performed; when inter-phase and inter-phase grounding faults occur, the overload blocking is released, the protection judgment is carried out, the fault line is cut off in combination with main protection, and for the accident overload, the blocking protection is carried out to guarantee that the false operation is not performed. The method disclosed by the invention can guarantee reliable blocking of the distance protection section III under the accident overload, reliable release of the distance protection section III during occurrence of the inter-phase fault, the inter-phase grounding fault and a fault of one-phase grounding through a small transition resistor, and reliable delayed release of the distance protection section III during occurrence of a fault of one-phase grounding through a large transition resistor, thereby guaranteeing that a power system safely and stably runs.

Description

The accident overload blocking method of territory distance protection III section of standing

Technical field

The invention belongs to the territory distance protection of electric power system station and control technology field, particularly a kind of accident overload blocking method being applied to station territory distance protection III section.

Background technology

Along with the sustainable growth of electricity needs, power grid heavy-load ruuning situation is more general.When one or more line tripping, the load of tripping operation circuit can be transferred on other working lines of Transmission Lines with Parallel Sections section, forms other working line overloads.Because this type of overload may be caused by fault, also may be caused by fault-free trip, therefore be referred to as accident overload.Power flow transfer overload is also referred to as in research in the past.

The feature that accident overload situation increases along with electric current usually, voltage reduces, impedance plane has similitude with fault, thus may be mistaken for fault by distance protection.Wherein, distance protection III section needs to provide backup protection far away to next stage circuit; thus there is comparatively high sensitivity, comprise for the ground distance protection III section of earth fault (comprising single-phase earthing, two phase ground and three-phase ground) and the phase distance protection III section for phase-to phase fault (comprising phase to phase fault, two phase ground and three-phase fault).Measurement impedance under accident overload is easier to enter active region; therefore transmission line distance protecting III section trips when non-faulting at accident overload; cause All other routes overload further and develop into cascading trip; be almost the only way which must be passed of large-scale blackout in recent years, serious threat is constituted to electric power netting safe running.

Existing accident overload identification is mainly distinguished three-phase overload and fault.Tradition adopts load restriction relay to hide maximum overload, and the method difficulty of adjusting is large, and definitely cannot distinguish on impedance plane.Patent CN101335450A and patent 101710696B utilizes separate lines protected data to distinguish overload and fault, can only distinguish three-phase overload and fault, and not easily adjust.

And based on Wide-area Measurement Information, contrast by tidal current prediction and measured value, and enumerate and search for contingency set to identify overload, but under multiple branch circuit excision event, the traffic and amount of calculation are comparatively large, and are difficult to exhaustive, and real-time and reliability have many uncertainties.

Patent CN103545930A proposes a kind of territory, station protected data acquisition method based on telemechanical apparatus and system thereof, can gather full station protected data.The present invention is based on this, propose a kind ofly to utilize local station domain information identification accident overload and the method for locking distance protection III section, single-phase overload and alternate overload and fault can be distinguished simultaneously.

Summary of the invention

The object of the invention is the weak point for overcoming existing overload identification and lock-out techniques; propose a kind of accident overload blocking method of territory distance protection III section of standing; the method makes full use of territory, station and shares information; the reliable locking under accident overload of distance protection III section can be ensured; in phase-to phase fault, alternate earth fault and single-phase reliably opening under little transition resistance earth fault; when single-phase through great transition grounding through resistance reliable time delay open, ensure that power system safety and stability runs.。

The accident overload blocking method of a kind of territory distance protection III section of standing that the present invention proposes, is characterized in that, upon the occurrence of a ground fault, open overload locking, carry out protection to judge and coordinate with main protection to excise faulty line, and for accident overload, latch-up protection is to ensure not malfunction; The method specifically comprises the following steps:

1) protection carries out 100ms ~ 200ms time delay after starting, and enters step 2);

2) first judge whether to have tripped, if tripped, then enter step 11); If also do not tripped, enter step 3);

3) the secondary side negative sequence voltage 3U of 3 times is compared ₂with the secondary side negative sequence voltage threshold value U arranged _2set(U _2setspan is 1V ~ 5V), if 3U ₂be less than or equal to U _2set, enter step 4); If 3U ₂be greater than U _2set, enter step 5);

4) judge whether three-phase starts according to ground distance protection III section algorithm, if three-phase starts, enter step 9); Otherwise enter step 11);

5) sending Dai Weinan equiva lent impedance Z is calculated with starting rear 1-2 cycle data _thev, according to Z _thevcarry out ground distance protection III section algorithm and judge that whether three-phase is at active region, if three-phase is not at active region, then enter step 11); If have at least one to be positioned at active region mutually, then carry out step 6);

Dai Weinan equiva lent impedance Z _thevcircular is as follows:

Extract bus negative sequence voltage, all inlet wire negative-sequence current sums calculating sending Dai Weinan equiva lent impedance Z _thevfor:

$\left\{\begin{array}{c}{Z}_{\mathrm{thev}}\left(k\right)=\frac{{\stackrel{\·}{U}}_2\left(k\right)}{\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\·}{I}}_{m2}\left(k\right)}\\ Z_{\mathrm{thev}}=\stackrel{\‾}{Z_{\mathrm{thev}}\left(k\right)},k=t_0+1,t_0+2,....,t_0+2N\end{array}\right.---\left(16\right)$

In above formula, for a kth bus negative sequence voltage that sampling is counted; be a m article of inlet wire kth negative-sequence current that sampling is counted, to flow out generatrix direction for positive direction, transformer station is total M bar inlet wire always, and addition can all inlet wire negative-sequence current sums z _thevk () is a kth sending Dai Weinan equiva lent impedance that sampling is counted; N is every cycle sampled point, t ₀for protection starting instance sample point numbering, to the Z that rear 2 cycles of starting are calculated _thevk () averaged obtains sending Dai Weinan equiva lent impedance Z _thev;

6) basis is by POC ₁, POC ₂and POC ₃the accident overload identical criterion POC of three criterion compositions identifies, works as POC ₁, POC ₂and POC ₃when can not satisfy condition, enter step 10) simultaneously; Work as POC ₁, POC ₂and POC ₃when satisfying condition simultaneously, then judge that ground distance protection III section is positioned at the number of phases of active region again, be positioned at active region if single-phase, carry out step 7); If two-phase is positioned at active region, carry out step 8); If three-phase is positioned at active region, carry out step 9);

POC ₁criterion is such as formula (2):

Wherein, Z _{Σ R Φ}for the earthmeter impedance parallel connection value of all outlets of transformer station; Z _{Σ R Φ Φ}for the alternate measurement impedance parallel connection value of all outlets of transformer station, O _tHfor POC ₁setting value (the O that criterion is arranged _tHspan is 1 ~ 5);

POC ₂criterion is such as formula (3), (4), (5):

$Z_{\mathrm{E\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ}}+3K_0{\stackrel{\·}{I}}_0}---\left(19\right)$

$Z_{\mathrm{E\Φ\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ\Φ}}}---\left(20\right)$

Wherein, θ is the reliable margin angle (θ span is 5 ° ~ 20 °) arranged, and P is active power, with be respectively sending emf phase and equivalent phase current, with be respectively the alternate electromotive force of sending and equivalent three-phase current;

POC ₃criterion is such as formula (6):

Wherein, Z _{set Φ}for ground distance protection III section impedance setting value, Z _{set Φ Φ}for phase distance protection III section impedance setting value, O _mAXfor POC ₃setting value (the O that criterion is arranged _mAXspan is 0.1 ~ 0.8);

7) be positioned at active region when single-phase, first carry out judging such as formula (7):

I ₀/I ₂＞O _D(22)

Wherein, I ₀for zero-sequence current, I ₂for negative-sequence current, O _dfor zero-sequence current and the threshold value (span is 0.1 ~ 0.8) of the ratio of negative-sequence current; If above formula does not meet, enter step 10); If above formula meet, then Open Dynamic, is specially and carries out additional delay, if time delay is not arrived, gets back to step 5) in re-start ground distance protection III section algorithm judge; If time delay is arrived, then export tripping operation, terminate;

8) when two-phase is positioned at active region, carry out alternate cosinusoidal voltage restrictive condition and judge such as formula (8):

U _ΦΦ≤0.5U _NN(23)

Wherein U _{Φ Φ}for line voltage, U _nNfor rated line voltage;

If do not meet formula (8), select phase current variation delta I _maxlarger one enters monophasic action district mutually judges, the ground distance protection III section of another phase of involution, then proceeds to step 7); If meet formula (8), then enter step 10);

9) when three-phase is positioned at active region, carry out the judgement of formula (23) equally, if do not meet formula (23), then enter step 11); If meet formula (23), then enter step 10);

10) ground distance protection III section is open, and after time delay 1s ~ 5s, outlet tripping operation, terminates;

11) involution ground distance protection III section, terminates.

The accident overload blocking method of the another kind station territory distance protection III section that the present invention proposes, it is characterized in that, when there is alternate and alternate earth fault, open overload locking, carry out protection to judge and coordinate with main protection to excise faulty line, and for accident overload, latch-up protection is to ensure not malfunction; The method specifically comprises the following steps:

1) protection carries out 100ms ~ 200ms time delay after starting, and enters step 2);

2) first judge whether to have tripped, if tripped, then enter step 9); If also do not tripped, enter step 3);

3) the secondary side negative sequence voltage 3U of 3 times is compared ₂with the secondary side negative sequence voltage threshold value U arranged _2set(U _2setspan is 1V ~ 5V), if 3U ₂be less than or equal to U _2set, enter step 4); If 3U ₂be greater than U _2set, enter step 5);

4) phase distance protection III section algorithm judges, then enters step 7);

5) sending Dai Weinan equiva lent impedance Z is calculated with starting rear 1-2 cycle data _thev, according to calculating Dai Weinan equiva lent impedance Z _thevcarrying out phase distance protection III section algorithm judges whether at active region, if not at active region, then enters step 9); If be positioned at active region, then carry out step 6);

Dai Weinan equiva lent impedance Z _thevcircular is as follows:

Extract bus negative sequence voltage, all inlet wire negative-sequence current sums calculating sending Dai Weinan equiva lent impedance Z _thevfor:

$\left\{\begin{array}{c}{Z}_{\mathrm{thev}}\left(k\right)=\frac{{\stackrel{\·}{U}}_2\left(k\right)}{\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\·}{I}}_{m2}\left(k\right)}\\ Z_{\mathrm{thev}}=\stackrel{\‾}{Z_{\mathrm{thev}}\left(k\right)},k=t_0+1,t_0+2,....,t_0+2N\end{array}\right.---\left(24\right)$

In above formula, for a kth bus negative sequence voltage that sampling is counted; be a m article of inlet wire kth negative-sequence current that sampling is counted, to flow out generatrix direction for positive direction, transformer station is total M bar inlet wire always, and addition can all inlet wire negative-sequence current sums z _thevk () is a kth sending Dai Weinan equiva lent impedance that sampling is counted; N is every cycle sampled point, t ₀for protection starting instance sample point numbering, to the Z that rear 2 cycles of starting are calculated _thevk () averaged obtains sending Dai Weinan equiva lent impedance Z _thev;

6) basis is by POC ₁, POC ₂and POC ₃the accident overload identical criterion POC of three criterion compositions identifies, works as POC ₁, POC ₂and POC ₃when can not satisfy condition, enter step 9) simultaneously; Work as POC ₁, POC ₂and POC ₃when satisfying condition, enter step 7) simultaneously

POC ₁criterion is such as formula (10):

Wherein, Z _{Σ R Φ}for the earthmeter impedance parallel connection value of all outlets of transformer station; Z _{Σ R Φ Φ}for the alternate measurement impedance parallel connection value of all outlets of transformer station, O _tHfor POC ₁setting value (the O that criterion is arranged _tHspan is 1 ~ 5).

POC ₂criterion is such as formula (11), (12), (13):

$Z_{\mathrm{E\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ}}+3K_0{\stackrel{\·}{I}}_0}---\left(27\right)$

$Z_{\mathrm{E\Φ\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ\Φ}}}---\left(28\right)$

Wherein, θ is the reliable margin angle (θ span is 5 ° ~ 20 °) arranged, and P is active power, with be respectively sending emf phase and equivalent phase current, with be respectively the alternate electromotive force of sending and equivalent three-phase current.

POC ₃criterion is such as formula (14):

Z _{set Φ}for ground distance protection III section impedance setting value, Z _{set Φ Φ}for phase distance protection III section impedance setting value, O _mAXfor POC ₃setting value (the O that criterion is arranged _mAXspan is 0.1 ~ 0.8).

7) carrying out alternate cosinusoidal voltage restrictive condition judges such as formula (15):

U _ΦΦ≤0.5U _NN(30)

Wherein U _{Φ Φ}for line voltage, U _nNfor rated line voltage.If meet above formula, enter step 8); If do not meet above formula, enter step 9);

8) phase distance protection III section is open, and after time delay 1s ~ 5s, outlet tripping operation, terminates;

9) involution phase distance protection III section, terminates.

Feature of the present invention and beneficial effect:

The feature of station of the present invention territory distance protection III section accident overload blocking method is: based on all line informations in territory, station, design overload locking method respectively for ground distance protection III section and phase distance protection III section.The method utilizes the electric information of all circuits of access in transformer station, computing system Dai Weinan equiva lent impedance, and devises exclusive POC criterion, make use of alternate cosinusoidal voltage restrictive condition simultaneously.Exclusive Open Dynamic condition is devised during monophasic action in ground distance protection III section.

Territory, station distance protection III section accident overload blocking method proposed by the invention, makes full use of territory, station and shares information, solve a difficult problem for the unreasonable tripping operation of distance protection III section under accident overload.The method can ensure the reliable locking under accident overload of distance protection III section; in phase-to phase fault, alternate earth fault and single-phase reliably opening under little transition resistance earth fault; when single-phase through great transition grounding through resistance reliable time delay open, ensure that power system safety and stability runs.

Accompanying drawing explanation

Fig. 1 is the ground distance protection III section accident overload locking flow chart of embodiments of the invention one;

Fig. 2 is the phase distance protection III section accident overload locking flow chart of embodiments of the invention two.

Embodiment

A kind of accident overload blocking method of territory distance protection III section of standing that the present invention proposes, by reference to the accompanying drawings and embodiment be described in detail as follows:

Embodiment one is the accident overload blocking method of ground distance III section, and in the present embodiment, setting protection starts rear time delay is 150ms, secondary side negative sequence voltage threshold value U _2setfor 3V, POC ₁the setting value O that criterion is arranged _tHbe 2, reliable margin angle θ gets 15 °, POC ₃the setting value O that criterion is arranged _mAXbe 0.3, the threshold value O of zero-sequence current and the ratio of negative-sequence current _dbe 0.45, after open ground distance protection III section, time delay is 1.5s;

Comprise the following steps:

1) protection carries out 150ms time delay after starting, and enters step 2);

2) first judge whether to have tripped, if tripped, then enter step 11); If also do not tripped, enter step 3);

3) the secondary side negative sequence voltage 3U of 3 times is compared ₂with 3V, if 3U ₂be less than or equal to 3V, enter step 4); If 3U ₂be greater than 3V, enter step 5);

4) judge whether three-phase starts according to ground distance protection III section algorithm, if be three-phase startup, enter step 9); Otherwise enter step 11);

5) sending Dai Weinan equiva lent impedance Z are calculated with starting rear 2 cycle data _thev, according to Z _thevcarry out ground distance protection III section algorithm and judge that whether three-phase is at active region, if three-phase is not at active region, then enter step 11); If have at least one to be positioned at active region mutually, then carry out step 6);

Dai Weinan equiva lent impedance Z _thevcircular is as follows:

Extract bus negative sequence voltage, all inlet wire negative-sequence current sums calculating sending Dai Weinan equiva lent impedance Z _thevfor:

$\left\{\begin{array}{c}{Z}_{\mathrm{thev}}\left(k\right)=\frac{{\stackrel{\·}{U}}_2\left(k\right)}{\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\·}{I}}_{m2}\left(k\right)}\\ Z_{\mathrm{thev}}=\stackrel{\‾}{Z_{\mathrm{thev}}\left(k\right)},k=t_0+1,t_0+2,....,t_0+2N\end{array}\right.---\left(31\right)$

In above formula, for a kth bus negative sequence voltage that sampling is counted; be a m article of inlet wire kth negative-sequence current that sampling is counted, to flow out generatrix direction for positive direction, transformer station is total M bar inlet wire always, and addition can all inlet wire negative-sequence current sums z _thevk () is a kth sending Dai Weinan equiva lent impedance that sampling is counted; N is every cycle sampled point, t ₀for protection starting instance sample point numbering, to the Z that rear 2 cycles of starting are calculated _thevk () averaged obtains sending Dai Weinan equiva lent impedance Z _thev;

6) basis is by POC ₁, POC ₂and POC ₃the accident overload identical criterion POC of three criterion compositions identifies, works as POC ₁, POC ₂and POC ₃when can not satisfy condition, enter step 10) simultaneously; Work as POC ₁, POC ₂and POC ₃when satisfying condition simultaneously, then judge that ground distance protection III section is positioned at the number of phases of active region again, be positioned at active region if single-phase, carry out step 7); If two-phase is positioned at active region, carry out step 8); If three-phase is positioned at active region, carry out step 9);

POC ₁criterion is such as formula (17):

Wherein, Z _{Σ R Φ}for the earthmeter impedance parallel connection value of all outlets of transformer station; Z _{Σ R Φ Φ}for the alternate measurement impedance parallel connection value of all outlets of transformer station.

POC ₂criterion is such as formula (18), (19), (20):

$Z_{\mathrm{E\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ}}+3K_0{\stackrel{\·}{I}}_0}---\left(34\right)$

$Z_{\mathrm{E\Φ\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ\Φ}}}---\left(35\right)$

Wherein, P is active power, with be respectively sending emf phase and equivalent phase current, with be respectively the alternate electromotive force of sending and equivalent three-phase current;

POC ₃criterion is such as formula (21):

Z _{set Φ}for ground distance protection III section impedance setting value, Z _{set Φ Φ}for phase distance protection III section impedance setting value.

7) be positioned at active region when single-phase, first carry out judging such as formula (22):

I ₀/I ₂＞0.45 (37)

Wherein I ₀for zero-sequence current, I ₂for negative-sequence current.If above formula does not meet, enter step 10); If above formula meet, then Open Dynamic, carries out additional delay, if time delay is not arrived, gets back to step 5) in re-start ground distance protection III section algorithm judge; If time delay is arrived, then export tripping operation, terminate;

8) when two-phase is positioned at active region, carry out alternate cosinusoidal voltage restrictive condition and judge such as formula (23):

U _ΦΦ≤0.5U _NN(38)

Wherein U _{Φ Φ}for line voltage, U _nNfor rated line voltage;

If do not meet formula (38), select phase current variation delta I _maxlarger one enters monophasic action district mutually judges, the ground distance protection III section of another phase of involution, then enters step 7); If meet formula (38), then enter step 10);

9) when three-phase is positioned at active region, the judgement of formula (38) is carried out equally.If do not meet formula (38), then enter step 11); If meet formula (38), then enter step 10);

10) ground distance protection III section is open, and after time delay 1.5s, outlet tripping operation, terminates;

11) involution ground distance protection III section, terminates.

Embodiment two is the accident overload blocking method of phase spacing III section, and in the present embodiment, setting protection starts rear time delay is 150ms, secondary side negative sequence voltage threshold value U _2setfor 3V, POC ₁the setting value O that criterion is arranged _tHbe 2, reliable margin angle θ gets 15 °, POC ₃the setting value O that criterion is arranged _mAXbe 0.3, after open ground distance protection III section, time delay is 1.5s;

Comprise the following steps:

1) protection carries out 150ms time delay after starting, and enters step 2);

2) first judge whether to have tripped, if tripped, then enter step 9); If also do not tripped, enter step 3);

3) the secondary side negative sequence voltage 3U of 3 times is compared ₂with 3V, if 3U ₂be less than or equal to 3V, enter step 4); If 3U ₂be greater than 3V, enter step 5);

4) phase distance protection III section algorithm judges, then enters step 7);

5) sending Dai Weinan equiva lent impedance Z are calculated with starting rear 2 cycle data _thev, according to calculating Dai Weinan equiva lent impedance Z _thevcarrying out phase distance protection III section algorithm judges whether at active region, if not at active region, then enters step 9); If be positioned at active region, then carry out step 6);

Dai Weinan equiva lent impedance Z _thevcircular is as follows:

Extract bus negative sequence voltage, all inlet wire negative-sequence current sums calculating sending Dai Weinan equiva lent impedance Z _thevfor:

$\left\{\begin{array}{c}{Z}_{\mathrm{thev}}\left(k\right)=\frac{{\stackrel{\·}{U}}_2\left(k\right)}{\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\·}{I}}_{m2}\left(k\right)}\\ Z_{\mathrm{thev}}=\stackrel{\‾}{Z_{\mathrm{thev}}\left(k\right)},k=t_0+1,t_0+2,....,t_0+2N\end{array}\right.---\left(39\right)$

In above formula, for a kth bus negative sequence voltage that sampling is counted; be a m article of inlet wire kth negative-sequence current that sampling is counted, to flow out generatrix direction for positive direction, transformer station is total M bar inlet wire always, and addition can all inlet wire negative-sequence current sums z _thevk () is a kth sending Dai Weinan equiva lent impedance that sampling is counted; N is every cycle sampled point, t ₀for protection starting instance sample point numbering, to the Z that rear 2 cycles of starting are calculated _thevk () averaged obtains sending Dai Weinan equiva lent impedance Z _thev;

6) basis is by POC ₁, POC ₂and POC ₃the accident overload identical criterion POC of three criterion compositions identifies, works as POC ₁, POC ₂and POC ₃when can not satisfy condition, enter step 9) simultaneously; Work as POC ₁, POC ₂and POC ₃when satisfying condition, enter step 7) simultaneously;

POC ₁criterion is such as formula (25):

Wherein, Z _{Σ R Φ}for the earthmeter impedance parallel connection value of all outlets of transformer station; Z _{Σ R Φ Φ}for the alternate measurement impedance parallel connection value of all outlets of transformer station.

POC ₂criterion is such as formula (26), (27), (28):

$Z_{\mathrm{E\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ}}+3K_0{\stackrel{\·}{I}}_0}---\left(42\right)$

$Z_{\mathrm{E\Φ\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ\Φ}}}---\left(43\right)$

Wherein, P is active power, with be respectively sending emf phase and equivalent phase current, with be respectively the alternate electromotive force of sending and equivalent three-phase current.

POC ₃criterion is such as formula (29):

Z _{set Φ}for ground distance protection III section impedance setting value, Z _{set Φ Φ}for phase distance protection III section impedance setting value.

7) carrying out alternate cosinusoidal voltage restrictive condition judges such as formula (30):

U _ΦΦ≤0.5U _NN(45)

Wherein U _{Φ Φ}for line voltage, U _nNfor rated line voltage.If meet above formula, enter step 8); If do not meet above formula, then enter step 9);

8) phase distance protection II I section is open, and after time delay 1.5s, outlet tripping operation, terminates.

9) involution phase distance protection II I section, terminates.

Claims (6)

1. an accident overload blocking method for territory distance protection III section of standing, is characterized in that, upon the occurrence of a ground fault, open overload locking, carry out protection to judge and coordinate with main protection to excise faulty line, and for accident overload, latch-up protection is to ensure not malfunction; Specifically comprise the following steps:

1) protection carries out 100ms ~ 200ms time delay after starting, and enters step 2);

2) first judge whether to have tripped, if tripped, then enter step 11); If also do not tripped, enter step 3);

3) the secondary side negative sequence voltage 3U of 3 times is compared ₂with the secondary side negative sequence voltage threshold value U arranged _2setif, 3U ₂be less than or equal to U _2set, enter step 4); If 3U ₂be greater than U _2set, enter step 5);

4) judge whether three-phase starts according to ground distance protection III section algorithm, if three-phase starts, enter step 9); Otherwise enter step 11);

5) sending Dai Weinan equiva lent impedance Z is calculated with starting rear 1-2 cycle data _thev, according to Z _thevcarry out ground distance protection III section algorithm and judge that whether three-phase is at active region, if three-phase is not at active region, then enter step 11); If have at least one to be positioned at active region mutually, then carry out step 6);

6) basis is by POC ₁, POC ₂and POC ₃the accident overload identical criterion POC of three criterion compositions identifies, works as POC ₁, POC ₂and POC ₃when can not satisfy condition, enter step 10) simultaneously; Work as POC ₁, POC ₂and POC ₃when satisfying condition simultaneously, then judge that ground distance protection III section is positioned at the number of phases of active region again, be positioned at active region if single-phase, carry out step 7); If two-phase is positioned at active region, carry out step 8); If three-phase is positioned at active region, carry out step 9);

7) be positioned at active region when single-phase, first carry out judging such as formula (7):

I ₀/I ₂＞O _D(1)

Wherein, I ₀for zero-sequence current, I ₂for negative-sequence current, O _dfor zero-sequence current and the threshold value (span is 0.1 ~ 0.8) of the ratio of negative-sequence current; If above formula does not meet, enter step 10); If above formula meet, then Open Dynamic, is specially and carries out additional delay, if time delay is not arrived, gets back to step 5) in re-start ground distance protection III section algorithm judge; If time delay is arrived, then export tripping operation, terminate;

8) when two-phase is positioned at active region, carry out alternate cosinusoidal voltage restrictive condition and judge such as formula (8):

U _ΦΦ≤0.5U _NN(2)

Wherein U _{Φ Φ}for line voltage, U _nNfor rated line voltage;

If do not meet formula (8), select phase current variation delta I _maxlarger one enters monophasic action district mutually judges, the ground distance protection III section of another phase of involution, then proceeds to step 7); If meet formula (8), then enter step 10);

9) when three-phase is positioned at active region, carry out the judgement of formula (8) equally, if do not meet formula (8), then enter step 11); If meet formula (8), then enter step 10);

10) ground distance protection III section is open, and after time delay 1s ~ 5s, outlet tripping operation, terminates;

11) involution ground distance protection III section, terminates.

2. method as claimed in claim 1, is characterized in that, described step 5) Dai Weinan equiva lent impedance Z _thevcircular is as follows:

Extract bus negative sequence voltage, all inlet wire negative-sequence current sums calculating sending Dai Weinan equiva lent impedance Z _thevfor:

$\left\{\begin{array}{c}{Z}_{\mathrm{thev}}\left(k\right)=\frac{{\stackrel{\·}{U}}_2\left(k\right)}{\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\·}{I}}_{m2}\left(k\right)}\\ Z_{\mathrm{thev}}=\stackrel{\‾}{Z_{\mathrm{thev}}\left(k\right)},k=t_0+1,t_0+2,....,t_0+2N\end{array}\right.---\left(3\right)$

In above formula, for a kth bus negative sequence voltage that sampling is counted; be a m article of inlet wire kth negative-sequence current that sampling is counted, to flow out generatrix direction for positive direction, transformer station is total M bar inlet wire always, and addition can all inlet wire negative-sequence current sums z _thevk () is a kth sending Dai Weinan equiva lent impedance that sampling is counted; N is every cycle sampled point, t ₀for protection starting instance sample point numbering, to the Z that rear 2 cycles of starting are calculated _thevk () averaged obtains sending Dai Weinan equiva lent impedance Z _thev.

3. method as claimed in claim 1, is characterized in that, described step 6) POC ₁criterion is such as formula (2):

Wherein, Z _{Σ R Φ}for the earthmeter impedance parallel connection value of all outlets of transformer station; Z _{Σ R Φ Φ}for the alternate measurement impedance parallel connection value of all outlets of transformer station, O _tHfor POC ₁the setting value that criterion is arranged, O _tHspan is 1 ~ 5;

Described POC ₂criterion is such as formula (3), (4), (5):

$Z_{\mathrm{E\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ}}+3K_0{\stackrel{\·}{I}}_0}---\left(6\right)$

$Z_{\mathrm{E\Φ\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ\Φ}}}---\left(7\right)$

Wherein, θ is the reliable margin angle arranged, and θ span is 5 ° ~ 20 °, and P is active power, with be respectively sending emf phase and equivalent phase current, with be respectively the alternate electromotive force of sending and equivalent three-phase current;

Described POC ₃criterion is such as formula (6):

Wherein, Z _{set Φ}for ground distance protection III section impedance setting value, Z _{set Φ Φ}for phase distance protection III section impedance setting value, O _mAXfor POC ₃the setting value that criterion is arranged, O _mAXspan is 0.1 ~ 0.8.

4. an accident overload blocking method for territory distance protection III section of standing, is characterized in that, when there is alternate and alternate earth fault, open overload locking, carry out protection to judge and coordinate with main protection to excise faulty line, and for accident overload, latch-up protection is to ensure not malfunction; The method specifically comprises the following steps:

1) protection carries out 100ms ~ 200ms time delay after starting, and enters step 2);

2) first judge whether to have tripped, if tripped, then enter step 9); If also do not tripped, enter step 3);

3) the secondary side negative sequence voltage 3U of 3 times is compared ₂with the secondary side negative sequence voltage threshold value U arranged _2setif, 3U ₂be less than or equal to U _2set, enter step 4); If 3U ₂be greater than U _2set, enter step 5);

4) phase distance protection III section algorithm judges, then enters step 7);

5) sending Dai Weinan equiva lent impedance Z is calculated with starting rear 1-2 cycle data _thev, according to calculating Dai Weinan equiva lent impedance Z _thevcarrying out phase distance protection III section algorithm judges whether at active region, if not at active region, then enters step 9); If be positioned at active region, then carry out step 6);

6) basis is by POC ₁, POC ₂and POC ₃the accident overload identical criterion POC of three criterion compositions identifies, works as POC ₁, POC ₂and POC ₃when can not satisfy condition, enter step 9) simultaneously; Work as POC ₁, POC ₂and POC ₃when satisfying condition, enter step 7) simultaneously

7) carrying out alternate cosinusoidal voltage restrictive condition judges such as formula (15):

U _ΦΦ≤0.5U _NN(9)

Wherein U _{Φ Φ}for line voltage, U _nNfor rated line voltage; If meet above formula, enter step 8); If do not meet above formula, enter step 9);

8) phase distance protection III section is open, and after time delay 1s ~ 5s, outlet tripping operation, terminates;

9) involution phase distance protection III section, terminates.

5. method as claimed in claim 4, is characterized in that, described step 5) Dai Weinan equiva lent impedance Z _thevcircular is as follows:

Extract bus negative sequence voltage, all inlet wire negative-sequence current sums calculating sending Dai Weinan equiva lent impedance Z _thevfor:

$\left\{\begin{array}{c}{Z}_{\mathrm{thev}}\left(k\right)=\frac{{\stackrel{\·}{U}}_2\left(k\right)}{\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\·}{I}}_{m2}\left(k\right)}\\ Z_{\mathrm{thev}}=\stackrel{\‾}{Z_{\mathrm{thev}}\left(k\right)},k=t_0+1,t_0+2,....,t_0+2N\end{array}\right.---\left(10\right)$

In above formula, for a kth bus negative sequence voltage that sampling is counted; be a m article of inlet wire kth negative-sequence current that sampling is counted, to flow out generatrix direction for positive direction, transformer station is total M bar inlet wire always, and addition can all inlet wire negative-sequence current sums z _thevk () is a kth sending Dai Weinan equiva lent impedance that sampling is counted; N is every cycle sampled point, t ₀for protection starting instance sample point numbering, to the Z that rear 2 cycles of starting are calculated _thevk () averaged obtains sending Dai Weinan equiva lent impedance Z _thev.

6. method as claimed in claim 4, is characterized in that, described step 6) POC ₁criterion is such as formula (10):

Wherein, Z _{Σ R Φ}for the earthmeter impedance parallel connection value of all outlets of transformer station; Z _{Σ R Φ Φ}for the alternate measurement impedance parallel connection value of all outlets of transformer station, O _tHfor POC ₁the setting value that criterion is arranged, O _tHspan is 1 ~ 5;

POC ₂criterion is such as formula (11), (12), (13):

$Z_{\mathrm{E\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ}}+3K_0{\stackrel{\·}{I}}_0}---\left(13\right)$

$Z_{\mathrm{E\Φ\Φ}}=\frac{{\stackrel{\·}{E}}_{\mathrm{\Φ\Φ}}}{{\stackrel{\·}{I}}_{\mathrm{\Φ\Φ}}}---\left(14\right)$

Wherein, θ is the reliable margin angle arranged, and θ span is 5 ° ~ 20 °, and P is active power, with be respectively sending emf phase and equivalent phase current, with be respectively the alternate electromotive force of sending and equivalent three-phase current;

POC ₃criterion is such as formula (14):

Z _{set Φ}for ground distance protection III section impedance setting value, Z _{set Φ Φ}for phase distance protection III section impedance setting value, O _mAXfor POC ₃the setting value that criterion is arranged, O _mAXspan is 0.1 ~ 0.8.