CN101650386B - Method and system for judging zero shift of short circuit current of extra-high voltage alternating-current system - Google Patents

Abstract

The invention discloses a method for judging the zero shift of the short circuit current of an extra-high voltage alternating-current system, which comprises the following steps: building an electromagnetic transient simulation model of an extra-high voltage alternating-current system; simulating various fault conditions, circuit protection actions and breaker open operation procedures, and carrying out electromagnetic transient simulation on fault procedures by utilizing the electromagnetic transient simulation model to obtain current waves flowing through a circuit breaker under various fault conditions; and judging whether the phenomenon of zero shift of the short circuit current occurs or not according to the current waves obtained by simulation. The invention also discloses a system for judging the zero shift of the short circuit current of an extra-high voltage alternating-current system. The method and the system thoroughly consider the arc-extinguishing property of the breaker, the work schedule of the breaker and other factors, and generally and exactly judge whether the phenomenon of zero shift of the short circuit current exists in the system.

Description

A kind of determination methods and system of extra-high-voltage alternating current system short-circuit current zero drift

Technical field

The present invention relates to the UHV transmission field, particularly relate to a kind of determination methods and system of extra-high-voltage alternating current system short-circuit current zero drift.

Background technology

When Power System Shortcuts, its short-circuit current contains AC compounent (periodic component) and DC component (aperiodic component).When isolating switch cut-off short-circuit current, its DC component caused the drift of short-circuit current zero crossing probably, prolonged and the arc extinguishing difficulty in the time of may causing arc extinguishing when serious.

In system for ultra-high voltage transmission, the easier appearance of zero point drift phenomenon of short-circuit current.Therefore, in the extra-high-voltage alternating current system, the influence that the short-circuit current zero point drift phenomenon that research judgement DC component causes is cut-off isolating switch is very necessary.

The principle of judging short-circuit current zero point drift phenomenon in the prior art is:

Set: load current is

The fault current AC compounent is Suppose t _fThe fault that constantly is short-circuited, its switching current as shown in Figure 1.Fig. 1 is typical zero point drift phenomenon synoptic diagram.

The size of its switching current DC component can be similar to formula (1) expression:

$I_{\mathrm{DC}}=|\sqrt{2}{I}_f\cos ({\mathrm{\ωt}}_f-{\mathrm{\θ}}_f)-\sqrt{2}{I}_S\cos ({\mathrm{\ωt}}_f-{\mathrm{\θ}}_S)|---\left(1\right)$

As can be known, the moment t of the size of DC component and short trouble generation _fRelevant, it concerns that as shown in Figure 2 its maximal value is: $I_{\mathrm{DC}\max }=|{\stackrel{\·}{I}}_f-{\stackrel{\·}{I}}_S|$

Electric current after short trouble takes place is as shown in Equation (2):

$i\left(t\right)=I_{\mathrm{DC}}\×e^{-(R/L)t}+k\left(t\right)\×\sqrt{2}{I}_f\cos (\mathrm{\ωt}-{\mathrm{\θ}}_f)---\left(2\right)$

Wherein, the fault current AC compounent attenuation coefficient of k (t) after for the influence of considering generator; L/R is the time constant of DC component decay; L and R be respectively see from the trouble spot into system reactance and resistance.

Because the system for ultra-high voltage transmission line resistance is less, the reactance of voltage device is bigger, so its time constant L/R is bigger, cause the DC component decay slower.

Can draw the condition that the zero point drift imagination may occur by formula (2) is:

$\frac{|{\stackrel{\·}{I}}_f-{\stackrel{\·}{I}}_S|}{\left|{\stackrel{\·}{I}}_f\right|}>k(t-t_0)\×e^{(R/L)t}---\left(3\right)$

By formula (3) as can be known, the condition that zero point drift occurs depends on to a great extent and is defined as k by the ratio of DC component and AC compounent _T, wherein:

$k_T=\frac{|{\stackrel{\·}{I}}_f-{\stackrel{\·}{I}}_S|}{\left|{\stackrel{\·}{I}}_f\right|}---\left(4\right)$

In general, k _TBig more, the ratio of DC component and AC compounent is big more, the easy more zero point drift imagination that occurs; Bigger K _TAppear at easily in the system that short-circuit current and load current are approaching, short-circuit current is less.

In the prior art, serve as the foundation of judging short-circuit current zero point drift possibility generally with formula (3), as shown in Figure 3, for having method flow diagram now based on the judgement short-circuit current zero point drift of formula (3).Described method specifically may further comprise the steps:

Step S301: based on system load flow and stablize data, calculate under the various possible methods of operation, flow through the load current of the isolating switch of investigating

Step S302: based on system load flow and stablize data, calculating the isolating switch of investigating when circuit is short-circuited fault, flow through the short-circuit current of isolating switch

Step S303:, calculate k according to formula (4) _T, according to k _TSize, judge whether to exist not zero crossing, be the risk of zero point drift in conjunction with formula (3).

But the described method of prior art is not considered the difference of DC component attenuation coefficient under different system, different faults condition.Because identical k _TUnder the condition, the DC component damping time constant is more little, and the short-circuit current zero crossing time is short more.

Simultaneously, existing method does not consider that faulty line two ends isolating switch action sequence is to the influence of zero point drift phenomenon in the real system.The alternate coupling that has electric current and voltage of three-phase alternating current transmission line of electricity, for example if A phase isolating switch successfully cut-offs, when then causing A phase short-circuit current to change, because coupling, can cause that also B, C phase current change to some extent, thereby the zero-crossing timing of circuit breaker current is produced certain influence.

Therefore, study the determination methods that a kind of brand-new extra-high-voltage alternating current system short-circuit current zero drifts about, take into full account factors such as breaker arc extinguishing performance, isolating switch work schedule, judging more comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon, is the technical matters that those skilled in the art are badly in need of solving.

Summary of the invention

Technical matters to be solved by this invention provides a kind of determination methods and system of extra-high-voltage alternating current system short-circuit current zero drift, take into full account factors such as breaker arc extinguishing performance, isolating switch work schedule, judge more comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

For solving the problems of the technologies described above, the invention provides a kind of determination methods of extra-high-voltage alternating current system short-circuit current zero drift, described method comprises:

Set up the electromagnetic transient simulation model of extra-high-voltage alternating current system;

Simulate the action of various fault conditions and route protection, breaker open operation process, adopt described electromagnetic transient simulation model that failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker;

The described current waveform that obtains according to emulation judges whether to occur the zero point drift phenomenon of short-circuit current; When the result of described judgement when being, set up the realistic model of faulty line protection model and two ends breaker open operation; According to the realistic model of described faulty line protection model and two ends breaker open operation,, judge by emulation whether zero point drift can cause the difficulty of cut-offfing of isolating switch in conjunction with fault type.

Preferably, described fault type is list wink fault, single fault or heterogeneous fault forever.

Preferably, when being single wink during fault, describedly judge by emulation whether zero point drift can cause that the difficulty of cut-offfing of isolating switch specifically comprises:

At random constantly, detect when random site along the line is a certain mutually singlephase earth fault to take place, the action of described faulty line protection model is sent sub-gate signal to both sides fault phase isolating switch respectively;

After described both sides fault phase isolating switch receives described sub-gate signal, in default very first time scope, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that the zero point drift meeting causes isolating switch to cut-off difficulty.

Preferably, when being single fault forever, describedly judge by emulation whether zero point drift can cause that the difficulty of cut-offfing of isolating switch specifically comprises:

At random constantly, detect when random site along the line is a certain mutually singlephase earth fault to take place, the action of described faulty line protection model is sent sub-gate signal to both sides fault phase isolating switch respectively;

After described both sides fault phase isolating switch receives described sub-gate signal, successfully cut-off, through default reclosing interval time, both sides fault phase isolating switch reclosing;

Described faulty line protection model moves once more, sends the order of three-phase separating brake to both sides fault phase isolating switch;

After described both sides fault phase isolating switch receives the order of described three-phase separating brake, in the second default time range, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that zero point drift causes isolating switch to cut-off difficulty.

Preferably, when being heterogeneous fault, describedly judge by emulation whether zero point drift can cause that the difficulty of cut-offfing of isolating switch specifically comprises:

At random constantly, when detecting random site along the line heterogeneous fault taking place, the action of described faulty line protection model sends sub-gate signal to the both sides three-phase breaker respectively;

After described both sides three-phase breaker receives described sub-gate signal, in the 3rd default time range, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that the zero point drift meeting causes isolating switch to cut-off difficulty.

Preferably, during the described electromagnetic transient simulation model of setting up the extra-high-voltage alternating current system, comprise following factor:

The method of operation of the structure of system and parameter, system; And system loss and computing method thereof; And abort situation; And fault type.

The present invention also provides a kind of judgement system of extra-high-voltage alternating current system short-circuit current zero drift, and described system comprises:

Transient emulation modelling unit is used to set up the electromagnetic transient simulation model of extra-high-voltage alternating current system;

The fault simulation unit, be used to simulate the action of various fault conditions and route protection, breaker open operation process, adopt described electromagnetic transient simulation model that failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker;

The drift judging unit is used for judging whether to occur according to the described current waveform that emulation obtains the zero point drift phenomenon of short-circuit current;

Emergency protection modelling unit, be used for when the judged result of described drift judging unit when being, set up the realistic model of faulty line protection model and two ends breaker open operation;

Cut-off difficult judging unit, be used for realistic model,, judge by emulation whether zero point drift can cause the difficulty of cut-offfing of isolating switch in conjunction with fault type according to described faulty line protection model and two ends breaker open operation.

Preferably, described fault type is list wink fault, single fault or heterogeneous fault forever.

Compared with prior art, the present invention has the following advantages:

The determination methods and the system of extra-high-voltage alternating current system short-circuit current zero drift of the present invention, by setting up the electromagnetic transient simulation model of extra-high-voltage alternating current system, various fault conditions carry out analog simulation, obtain to flow through under the various fault conditions current waveform of line-breaker; The described current waveform that obtains according to emulation judges whether to occur the zero point drift phenomenon of short-circuit current.

Compared with prior art, the method of the invention and system are judged zero point drift based on the electromagnetic transient simulation model, because in described electro-magnetic transient model, factors such as isolating switch arc extinction performance, isolating switch work schedule have been considered, therefore, the method for the invention and system can judge comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

Description of drawings

Fig. 1 is typical zero point drift phenomenon synoptic diagram;

The synoptic diagram that concerns of Fig. 2 DC component size and fault moment when the zero point drift phenomenon takes place;

Fig. 3 is the method flow diagram of the judgement short-circuit current zero point drift of prior art;

Fig. 4 is the determination methods process flow diagram of the extra-high-voltage alternating current system short-circuit current zero drift of the embodiment of the invention;

Fig. 5 a is the current waveform figure of the A phase isolating switch that adopts electromagnetic transient simulation model emulation of the present invention and obtain;

Fig. 5 b is the current waveform figure of the B phase isolating switch that adopts electromagnetic transient simulation model emulation of the present invention and obtain;

Fig. 5 c is the current waveform figure of the C phase isolating switch that adopts electromagnetic transient simulation model emulation of the present invention and obtain;

Fig. 6 a is the current waveform that cut-offs A phase isolating switch under single fault condition forever;

Fig. 6 b is the current waveform that cut-offs B phase isolating switch under single fault condition forever;

Fig. 6 c is the current waveform that cut-offs C phase isolating switch under single fault condition forever;

Fig. 7 is the judgement system construction drawing of extra-high-voltage alternating current system short-circuit current zero drift of the present invention.

Embodiment

Technical matters to be solved by this invention provides a kind of determination methods of extra-high-voltage alternating current system short-circuit current zero drift, take into full account factors such as breaker arc extinguishing performance, isolating switch work schedule, judge more comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

With reference to Fig. 4, be the determination methods process flow diagram of the described extra-high-voltage alternating current system short-circuit of embodiment of the invention current zero drift.Described method mainly may further comprise the steps:

Step S401: the electromagnetic transient simulation model of setting up extra-high-voltage alternating current system short-circuit current zero drift phenomenon;

Determination methods of the present invention is based on described electromagnetic transient simulation model.At first need to set up the electromagnetic transient simulation model, the foundation of described model needs to consider following several factors:

(1) method of operation of the structure of system and parameter, system, especially system boot, trend size and Orientation etc.;

(2) system loss and computing method thereof;

System loss is very big to the influence of short-circuit current DC component time constant, and it has accurately been calculated big difficulty.If ignore too much system loss, may cause the time constant deviation ratio that calculates bigger.Therefore, when calculating, can mainly consider the influence of following loss:

(a) transformer loss;

(b) fault scratch start road resistance;

(c) stake resistance: during system generation earth fault, stake resistance has a significant effect to DC component time constant and current over-zero time; And stake resistance is relevant with factors such as abort situation, geographical conditions;

In addition, also have some other loss in the system, but be difficult to take into account fully.

(3) abort situation: the different faults position can cause a great difference of short-circuit current, needs the fault that takes place on consideration each position along the line;

(4) fault type: the different faults type all has bigger influence to the AC compounent of short-circuit current DC component time constant and short-circuit current, in order to grasp DC component time constant and zero point drift problem comprehensively, need to consider following several fault types: a phase ground connection; The two-phase phase fault; The two phase ground short circuit; Three-phase shortcircuit; The three-phase ground short circuit.

Step S402: simulate the action of various fault conditions and route protection, breaker open operation process, adopt described electromagnetic transient simulation model that failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker;

Step S403: the zero point drift phenomenon that judges whether to occur short-circuit current according to the current waveform of described electromagnetic transient simulation model output.

Specify the detailed process of step S402 and step S403 below with legend:

On the basis of step S401, failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker.With figure shown in Fig. 5 a to Fig. 5 c is that example describes.

Referring to Fig. 5 a to Fig. 5 c, be respectively the current waveform figure of the typical A that adopts electromagnetic transient simulation model emulation of the present invention to obtain, B, C three-phase breaker.Described oscillogram is: certain extra high voltage line middle part takes place under the singlephase earth fault condition, does not consider under the breaker open operation condition, flows through the current waveform of circuit one side A, B, C three-phase breaker respectively.Shown in Fig. 5 c: as described in C phase circuit breaker current continue not zero passage of 120ms approximately, promptly have the zero point drift phenomenon.Therefore, can judge that according to Fig. 5 c obtaining C phase isolating switch the current zero drift phenomenon can occur.

So far, the method for the invention can be judged the short-circuit current zero point drift phenomenon of extra-high-voltage alternating current system.The method of the invention is judged zero point drift based on the electromagnetic transient simulation model, because in described electro-magnetic transient model, factors such as isolating switch arc extinction performance, isolating switch work schedule have been considered, therefore, the method for the invention can judge comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

Further, when the judged result among the step S403 when being, the zero point drift phenomenon promptly takes place, whether the method for the invention can also can cause that the difficulty of cut-offfing of isolating switch judges to the zero point drift phenomenon that takes place.Because the negative consequence that the zero point drift phenomenon may cause is the failure of cut-offfing of line-breaker.Therefore, after judging whether system the zero point drift phenomenon occurs, can further judge whether to occur the difficulty of cut-offfing of isolating switch.If the judged result among the step S403 is not, then process ends.

Step S404: the realistic model of setting up faulty line protection model and two ends breaker open operation;

Whether can cause cut-offfing at need of isolating switch in analysis zero point drift, should consider breaker open operation randomness successively in two ends under the line fault condition comprehensively, and consider three-phase breaker separating brake priority dispersiveness constantly comprehensively.Occur when the short-circuit current that flows through certain phase isolating switch under the condition of zero point drift, other phase isolating switchs carry out in the dropout current operating process, because alternate existence coupling, often changed the zero point drift phase current, may make drift current transfer zero passage to, thereby make isolating switch possess the condition of cut-offfing by zero passage not.

Therefore, in carrying out the judgement whether isolating switch cut-off difficulty, need be on the basis of step S401, increase the realistic model of faulty line protection model and two ends breaker open operation.

Step S405:,, judge by emulation whether zero point drift can cause the difficulty of cut-offfing of isolating switch in conjunction with fault type according to model described in the step S404.

Analyze the difficulty of cut-offfing whether the zero point drift phenomenon can cause isolating switch, should be taken into account in the separating brake process of isolating switch that (for example: all possess the arc extinguishing ability 20ms), promptly current over-zero in this time range can cut-off short-circuit current in the certain hour scope.At this moment, on step S401 and the described model based of S404, the system failure is carried out electromagnetic transient simulation, judge whether zero point drift can cause that isolating switch cut-offs difficulty.

For different fault types, described by emulation judge zero point drift whether can cause isolating switch cut-off the difficulty detailed process be different.In the embodiment of the invention, select three kinds of common fault types to be described in detail respectively:

(1) list wink fault

Step S405_1a: at random constantly, detect when random site along the line is a certain mutually singlephase earth fault to take place, the action of described faulty line protection model is sent sub-gate signal to both sides fault phase isolating switch respectively;

The described a certain singlephase earth fault that takes place mutually of random site along the line that detects is meant: detect the current waveform that described electromagnetic transient simulation model emulation obtains, when certain phase current values occurring and exceed default normal range, determine that singlephase earth fault takes place mutually for this.

Step S405_1b: after described both sides fault phase isolating switch receives described sub-gate signal, in default very first time scope, the circuit breaker current waveform according to two ends breaker open operation realistic model emulation obtains judges whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that the zero point drift meeting causes isolating switch to cut-off difficulty.

(2) single fault forever

Step S405_2a: at random constantly, detect when random site along the line is a certain mutually singlephase earth fault to take place, the action of described faulty line protection model is sent sub-gate signal to both sides fault phase isolating switch respectively;

Step S405_2b: after described both sides fault phase isolating switch receives described sub-gate signal, successfully cut-off, through default reclosing interval time, both sides fault phase isolating switch reclosing;

Wherein, described default reclosure time can specifically be set according to concrete applied environment.Can get described reclosure time in the embodiment of the invention is 0.7～1s.

Step S405_2c: described faulty line protection model moves once more, sends the order of three-phase separating brake to both sides fault phase isolating switch;

Step S405_2d: after described both sides fault phase isolating switch receives the order of described three-phase separating brake, in the second default time range, the circuit breaker current waveform that obtains according to two ends breaker open operation realistic model emulation, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that zero point drift causes isolating switch to cut-off difficulty.

Wherein, the value of described default second time range is relevant with the performance parameter of isolating switch, and its concrete numerical value can specifically be set according to concrete applied environment.Can get described second time range in the embodiment of the invention is 30～50s.

(3) heterogeneous fault

Step S405_3a: at random constantly, when detecting random site along the line heterogeneous fault taking place, the action of described faulty line protection model sends sub-gate signal to the both sides three-phase breaker respectively;

Wherein, described heterogeneous fault comprises: two-phase phase fault, two phase ground short circuit, three-phase shortcircuit, three-phase ground short circuit etc.

Step S405_3b: after described both sides three-phase breaker receives described sub-gate signal, in the 3rd default time range, the circuit breaker current waveform according to two ends breaker open operation realistic model emulation obtains judges whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that the zero point drift meeting causes isolating switch to cut-off difficulty.

Wherein, the value of described default the 3rd time range is relevant with the performance parameter of isolating switch, and its concrete numerical value can specifically be set according to concrete applied environment.Can get described second time range in the embodiment of the invention is 30～50s.

Under regard to step S404 and be specifically described with legend to the described content of step S405.With reference to Fig. 6 a to Fig. 6 c, be respectively the current waveform that cut-offs A, B, C three-phase breaker under single fault condition forever.Described waveform is: certain extra high voltage line middle part takes place under the singlephase earth fault condition, and there is the zero point drift phenomenon in C phase circuit breaker current.Because electric current is zero passage not, possible isolating switch is difficult to cut-off.At this moment, consider the three-phase breaker separating brake, about 50ms after the fault, when A mutually with B mutually behind the separating brake, owing to alternate coupling, the C phase current waveform develops into zero passage very soon by zero passage not, illustrates that isolating switch can normally cut-off.

According to example explanation shown in Figure 6, even there is the zero point drift phenomenon, because isolating switch moves, reaches the influence of alternate coupling, isolating switch still may normally cut-off.Adopt the method for the invention to consider that faulty line both sides isolating switch action sequence is to the influence of zero point drift phenomenon in the real system, considered that isolating switch cut-offs the influence of arc quenching characteristic, can judge accurately whether short-circuit current zero point drift phenomenon can cause the difficulty of cut-offfing of isolating switch.

Whether the method for the invention can cause isolating switch to cut-off at need in analysis zero point drift, considers both sides breaker open operation priority dispersiveness constantly under the line fault condition comprehensively, considers three-phase breaker separating brake priority dispersiveness constantly comprehensively.When the short-circuit current that flows through certain phase isolating switch occurs under the zero point drift condition, behind other isolating switch dropout currents, because alternate existence coupling, and then changed the drift phase current, may make electric current become zero passage, thereby make isolating switch possess the condition of cut-offfing by zero passage not.

The determination methods of extra-high-voltage alternating current system short-circuit current zero drift of the present invention, by setting up the electromagnetic transient simulation model of extra-high-voltage alternating current system, various fault conditions carry out analog simulation, obtain to flow through under the various fault conditions current waveform of line-breaker; The described current waveform that obtains according to emulation judges whether to occur the zero point drift phenomenon of short-circuit current.

Compared with prior art, the method of the invention is judged zero point drift based on the electromagnetic transient simulation model, because in described electro-magnetic transient model, factors such as isolating switch arc extinction performance, isolating switch work schedule have been considered, therefore, the method for the invention can judge comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

Simultaneously, whether the method for the invention can also further to causing that isolating switch cut-offs difficulty and judges after judgement obtains existing the zero point drift phenomenon.Adopt the method for the invention can recognize correctly that zero point drift phenomenon and isolating switch cut-off getting in touch and distinguishing between the difficulty, be that the zero point drift phenomenon only is to cause isolating switch to cut-off the possible condition of difficulty, rather than necessary condition, proposed simultaneously a kind of judge zero point drift whether can cause isolating switch cut-off the difficulty new method.

Corresponding to the determination methods of extra-high-voltage alternating current system short-circuit current zero drift provided by the invention, the present invention also provides a kind of judgement system of extra-high-voltage alternating current system short-circuit current zero drift.

With reference to Fig. 7, be the judgement system construction drawing of extra-high-voltage alternating current system short-circuit current zero drift of the present invention.Described system specifically comprises: transient emulation modelling unit 701, fault simulation unit 702 and drift judging unit 703.

Described transient emulation modelling unit 701 is used to set up the electromagnetic transient simulation model of extra-high-voltage alternating current system;

When setting up the electromagnetic transient simulation model, need to consider following several factors:

(1) method of operation of the structure of system and parameter, system, especially system boot, trend size and Orientation etc.;

(2) system loss and computing method thereof; During calculating, can mainly consider the influence of following loss: transformer loss; Fault scratch start road resistance; Stake resistance.

(3) abort situation: the different faults position can cause a great difference of short-circuit current, needs the fault that takes place on consideration each position along the line;

(4) fault type: consider following several fault types: a phase ground connection; The two-phase phase fault; The two phase ground short circuit; Three-phase shortcircuit; The three-phase ground short circuit.

Described fault simulation unit 702, be used to simulate the action of various fault conditions and route protection, breaker open operation process, adopt described electromagnetic transient simulation model that failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker;

Described drift judging unit 703 is used for judging whether to occur according to the described current waveform that emulation obtains the zero point drift phenomenon of short-circuit current.

The short-circuit current zero point drift phenomenon of extra-high-voltage alternating current system can be judged by system of the present invention.System of the present invention is judged zero point drift based on the electromagnetic transient simulation model, because in described electro-magnetic transient model, factors such as isolating switch arc extinction performance, isolating switch work schedule have been considered, therefore, system of the present invention can judge comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

Further, system of the present invention can further include cut-offs difficult judging unit, when the judged result of described drift judging unit 703 when being, the zero point drift phenomenon promptly takes place, whether can cause that to the zero point drift phenomenon that takes place the difficulty of cut-offfing of isolating switch judges.Because the negative consequence that the zero point drift phenomenon may cause is the failure of cut-offfing of line-breaker.Therefore, after judging whether system the zero point drift phenomenon occurs, can further judge whether to occur the difficulty of cut-offfing of isolating switch.

Still referring to shown in Figure 7, described system further comprises: emergency protection modelling unit 704 and cut-off difficult judging unit 705.

Described emergency protection modelling unit 704, be used for when the judged result of described drift judging unit when being, set up the realistic model of faulty line protection model and two ends breaker open operation;

Describedly cut-off difficult judging unit 705, be used for realistic model,, judge by emulation whether zero point drift can cause the difficulty of cut-offfing of isolating switch in conjunction with fault type according to described faulty line protection model and two ends breaker open operation.

Analyze the difficulty of cut-offfing whether the zero point drift phenomenon can cause isolating switch, should be taken into account in the separating brake process of isolating switch that (for example: all possess the arc extinguishing ability 20ms), promptly current over-zero in this time range can cut-off short-circuit current in the certain hour scope.At this moment, on the model based of system of the present invention, the system failure is carried out electromagnetic transient simulation, judge whether zero point drift can cause that isolating switch cut-offs difficulty.

For different fault types, described cut-off difficult judging unit 705 by emulation judge zero point drift whether can cause isolating switch cut-off the difficulty detailed process be different.In the embodiment of the invention, select three kinds of common fault types, be respectively list wink fault, single fault or heterogeneous fault forever.The process of describing among its concrete deterministic process and the method embodiment is identical.

The judgement system of extra-high-voltage alternating current system short-circuit current zero drift of the present invention, by setting up the electromagnetic transient simulation model of extra-high-voltage alternating current system, various fault conditions carry out analog simulation, obtain to flow through under the various fault conditions current waveform of line-breaker; The described current waveform that obtains according to emulation judges whether to occur the zero point drift phenomenon of short-circuit current.

Compared with prior art, system of the present invention is judged zero point drift based on the electromagnetic transient simulation model, because in described electro-magnetic transient model, factors such as isolating switch arc extinction performance, isolating switch work schedule have been considered, therefore, system of the present invention can judge comprehensively and accurately whether system exists short-circuit current zero point drift phenomenon.

Simultaneously, whether system of the present invention can also further to causing that isolating switch cut-offs difficulty and judges after judgement obtains existing the zero point drift phenomenon.Adopt system of the present invention can recognize correctly that zero point drift phenomenon and isolating switch cut-off getting in touch and distinguishing between the difficulty, i.e. zero point drift phenomenon only is to cause isolating switch to cut-off difficult possible condition, rather than necessary condition.

More than to the determination methods and the system of a kind of extra-high-voltage alternating current system short-circuit current zero drift provided by the present invention, be described in detail, used specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (8)

1. the determination methods of extra-high-voltage alternating current system short-circuit current zero drift is characterized in that described method comprises:

Set up the electromagnetic transient simulation model of extra-high-voltage alternating current system;

Simulate the action of various fault conditions and route protection, breaker open operation process, adopt described electromagnetic transient simulation model that failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker;

The described current waveform that obtains according to emulation judges whether to occur the zero point drift phenomenon of short-circuit current; When the result of described judgement when being, set up the realistic model of faulty line protection model and two ends breaker open operation; According to the realistic model of described faulty line protection model and two ends breaker open operation,, judge by emulation whether zero point drift can cause the difficulty of cut-offfing of isolating switch in conjunction with fault type.

2. method according to claim 1 is characterized in that, described fault type is list wink fault, single fault or heterogeneous fault forever.

3. method according to claim 2 is characterized in that, when being single wink during fault, describedly judges by emulation whether zero point drift can cause that the difficulty of cut-offfing of isolating switch specifically comprises:

At random constantly, detect when random site along the line is a certain mutually singlephase earth fault to take place, the action of described faulty line protection model is sent sub-gate signal to both sides fault phase isolating switch respectively;

After described both sides fault phase isolating switch receives described sub-gate signal, in default very first time scope, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that the zero point drift meeting causes isolating switch to cut-off difficulty.

4. method according to claim 2 is characterized in that, when being single fault forever, describedly judges by emulation whether zero point drift can cause that the difficulty of cut-offfing of isolating switch specifically comprises:

At random constantly, detect when random site along the line is a certain mutually singlephase earth fault to take place, the action of described faulty line protection model is sent sub-gate signal to both sides fault phase isolating switch respectively;

After described both sides fault phase isolating switch receives described sub-gate signal, successfully cut-off, through default reclosing interval time, both sides fault phase isolating switch reclosing;

Described faulty line protection model moves once more, sends the order of three-phase separating brake to both sides fault phase isolating switch;

After described both sides fault phase isolating switch receives the order of described three-phase separating brake, in the second default time range, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that zero point drift causes isolating switch to cut-off difficulty.

5. method according to claim 2 is characterized in that, when being heterogeneous fault, describedly judges by emulation whether zero point drift can cause that the difficulty of cut-offfing of isolating switch specifically comprises:

At random constantly, when detecting random site along the line heterogeneous fault taking place, the action of described faulty line protection model sends sub-gate signal to the both sides three-phase breaker respectively;

After described both sides three-phase breaker receives described sub-gate signal, in the 3rd default time range, judge whether to exist current zero-crossing point, if thinking can successful separating brake; If not, think that the zero point drift meeting causes isolating switch to cut-off difficulty.

6. method according to claim 1 is characterized in that, during the described electromagnetic transient simulation model of setting up the extra-high-voltage alternating current system, comprises following factor:

The method of operation of the structure of system and parameter, system; And system loss and computing method thereof; And abort situation; And fault type.

7. the judgement system of extra-high-voltage alternating current system short-circuit current zero drift is characterized in that described system comprises:

Transient emulation modelling unit is used to set up the electromagnetic transient simulation model of extra-high-voltage alternating current system;

The fault simulation unit, be used to simulate the action of various fault conditions and route protection, breaker open operation process, adopt described electromagnetic transient simulation model that failure process is carried out electromagnetic transient simulation, obtain to flow through under the various fault conditions current waveform of line-breaker;

The drift judging unit is used for judging whether to occur according to the described current waveform that emulation obtains the zero point drift phenomenon of short-circuit current;

Emergency protection modelling unit, be used for when the judged result of described drift judging unit when being, set up the realistic model of faulty line protection model and two ends breaker open operation;

Cut-off difficult judging unit, be used for realistic model,, judge by emulation whether zero point drift can cause the difficulty of cut-offfing of isolating switch in conjunction with fault type according to described faulty line protection model and two ends breaker open operation.

8. system according to claim 7 is characterized in that, described fault type is list wink fault, single fault or heterogeneous fault forever.

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