CN102420420A - Single-phase grounding protection method and system - Google Patents
Single-phase grounding protection method and system Download PDFInfo
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- CN102420420A CN102420420A CN2011104003132A CN201110400313A CN102420420A CN 102420420 A CN102420420 A CN 102420420A CN 2011104003132 A CN2011104003132 A CN 2011104003132A CN 201110400313 A CN201110400313 A CN 201110400313A CN 102420420 A CN102420420 A CN 102420420A
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Abstract
The invention provides a single-phase grounding protection method which is used for judging and isolating a single-phase grounding fault of a small-current grounding system. The single-phase grounding protection method comprises the following steps of: 102, synchronously acquiring the power frequency voltage of a bus of the small-current grounding system and current traveling waves of all outgoing lines corresponding to the bus in real time; 104, when the small-current grounding system is disturbed, determining a disturbance outgoing line according to the current traveling waves of all the outgoing lines; 106, determining whether the small-current grounding system has the single-phase grounding fault according to the power frequency voltage; and 108, determining that the disturbance outgoing line is a faulted outgoing line if the small-current grounding system has the single-phase grounding fault, sending a tripping instruction and insolating the faulted outgoing line. Correspondingly, the invention also provides a single-phase grounding protection system. By the single-phase grounding protection method and the single-phase grounding protection system, a requirement for judging the single-phase grounding fault of the small-current grounding system and a requirement for quick, reliable, sensitive and selective isolation can be met.
Description
Technical field
The present invention relates to field of relay protection in power, in particular to a kind of one-phase ground protection method and system.
Background technology
Small current neutral grounding system is meant when single phase ground fault takes place, the system that fault current is less, specifically refer to isolated neutral, neutral point through arc suppression coil or neutral point through the high resistance grounding system, be commonly called as small current system.Small current system generation single phase ground fault, because of not constituting short-circuit loop, fault current is little, and existing overcurrent protection can't precision maneuver isolated fault circuit.But according to statistics, single phase ground fault accounts for more than 70% of whole all faults of distribution system.In case the generation single phase ground fault, as can not in time eliminating fault, the fault electric arc of fault point maybe burning apparatus, and causes phase-to phase fault, and therefore the expansion accident is necessary to study the one-phase ground protection technology of small current neutral grounding system.
Around the single phase ground fault problem of small current system, domestic and international research person has carried out for a long time research widely, but it is technical mainly to concentrate on single-phase grounding selecting.The single-phase grounding selecting technology is on basis that single-phase earthing causes has been confirmed in disturbance, to launch, main research be to select ground path how sensitive and accurately, even single-phase earthing does not take place in the system, falsely dropped, also too big problem not.And one-phase ground protection is that single-phase earthing has taken place in the requirement system, must judge the fault zone accurately and reliably, isolates ground path fast; Single-phase earthing does not take place in the system, and reliably locking of protection can not malfunction.Therefore, one-phase ground protection has higher requirement than single-phase grounding selecting.
Therefore, be necessary to propose a kind of one-phase ground protection technology, can satisfy judgement single-phase grounded malfunction in grounded system of low current, and fast, reliable, sensitive, insulation request selectively.
Summary of the invention
The present invention just is being based on the problems referred to above, has proposed a kind of one-phase ground protection technology, can satisfy the judgement to single-phase grounded malfunction in grounded system of low current, and fast, reliable, sensitive, insulation request selectively.
In view of this; The present invention proposes a kind of one-phase ground protection method; Be used for single-phase grounded malfunction in grounded system of low current is judged and isolated; Comprise: step 102, the current traveling wave of all outlets that the power-frequency voltage of the bus of the said small current neutral grounding system of synchronous acquisition and said bus are corresponding in real time; Step 104 when in said small current neutral grounding system, disturbance taking place, according to the current traveling wave of said all outlets, is confirmed the disturbance outlet; Step 106 according to said power-frequency voltage, confirms whether said small current neutral grounding system single phase ground fault takes place; Step 108 when confirming said small current neutral grounding system generation single phase ground fault, confirms that said disturbance outlet is the fault outlet, sends trip command, isolates said fault outlet.In this technical scheme, when small current neutral grounding system normally moves, the three-phase voltage symmetry.When single-phase earthing took place, the ground connection phase voltage reduced, and perfected phase voltage and raise.According to detected voltage characteristic, can discern whether single-phase earthing has taken place in the small current neutral grounding system.When single-phase earthing takes place, earth point will be created in the current traveling wave of propagating in the system, and wherein, the initial polarity of traveling wave of the fault current of ground path is with to perfect circuit opposite, and the fault current initial row wave amplitude of ground path is greater than perfecting circuit.Thereby, can be through to the real-time collection and the detection of power-frequency voltage and current traveling wave, thus whether realization is to single phase ground fault has taken place in the small current neutral grounding system having discerned and having judged.
In technique scheme, preferably, in said step 102, said power-frequency voltage is to utilize the three-phase voltage of the said bus that voltage transformer collects and the open delta voltage of said voltage transformer.In this technical scheme, through voltage transformer power-frequency voltage is detected, simultaneously,, also can raise at the open delta voltage of voltage transformer if when breaking down, then can be with whether surpassing predetermined threshold value, as judging a condition that whether breaks down.
In technique scheme, preferably, in said step 102, utilize zero sequence current mutual inductor to gather the current traveling wave of said all outlets.
In technique scheme; Preferably; In said step 104; The process of the said disturbance outlet of said affirmation comprises: in the current traveling wave of said all outlets, the outlet that the amplitude of selection current traveling wave is maximum and/or the polarity of current traveling wave are different from the outlet of the polarity of other current traveling waves, as said disturbance outlet.In this technical scheme,, will be created in the fault traveling wave of propagating in the system in the fault point when small current neutral grounding system generation single-phase earthing; At the wave impedance discontinuity point; Like the bus place of transformer station, catadioptric will take place in this fault traveling wave, and refraction is advanced in the outlet of other normal operations.Therefore, single-phase earthing takes place in small current neutral grounding system after, be installed in instrument transformer in all outlets of transformer station with this fault traveling wave of perception.The travelling wave signal that route selection utilizes among the present invention is the initial row ripple of fault generating; With regard to the current traveling wave in all outlets on being connected the same bus of transformer station; Current traveling wave in the outlet of generation single-phase earthing is to bus from line flows; Be sources of the current traveling wave that produces in other normal operation outlets, and the current traveling wave in the outlet of normal operation being for to flow to circuit from bus, is the part of the current traveling wave in the outlet of generation single-phase earthing; Therefore; The current traveling wave amplitude that takes place in the outlet of single-phase earthing is maximum, the current traveling wave in the outlet of normal operation, and it is opposite that the polarity of the current traveling wave in the outlet of current traveling wave polarity and normal operation in the outlet of single-phase earthing takes place.
In technique scheme; Preferably, in said step 106, confirm that the process of said small current neutral grounding system generation single phase ground fault comprises: if said open delta voltage is greater than first predeterminated voltage; And in said three-phase voltage; One phase voltage is lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage, then confirms said small current neutral grounding system generation single phase ground fault.In this technical scheme, because when breaking down, open delta voltage can raise on the one hand, therefore it is set one first predeterminated voltage, as the threshold value of judging; On the other hand, in three-phase voltage, if there is a ground connection phase, then the voltage of this ground connection phase reduces, and other sound mutually then voltage raise, thereby can set second predeterminated voltage and the 3rd predeterminated voltage respectively as the threshold value of judging.
According to another aspect of the invention; A kind of one-phase ground protection system has also been proposed; Be used for single-phase grounded malfunction in grounded system of low current is judged and isolated, comprise: voltage collecting device, the power-frequency voltage of the bus of the said small current neutral grounding system of synchronous acquisition in real time; The current traveling wave harvester, the current traveling wave of all outlets that the said bus of synchronous acquisition is corresponding in real time; Disturbance outlet judgment means, when disturbance took place in said small current neutral grounding system, the current traveling wave of said all outlets of gathering according to said current traveling wave harvester was judged the disturbance outlet; The earth fault judgment means according to the said power-frequency voltage that said voltage collecting device is gathered, judges whether said small current neutral grounding system single phase ground fault takes place; Spacer assembly; Judge in said earth fault judgment means under the situation of said small current neutral grounding system generation single phase ground fault; Confirm that the said disturbance outlet that said disturbance outlet judgment means is judged is the fault outlet, and send trip command, isolate said fault outlet.In this technical scheme, when small current neutral grounding system normally moves, the three-phase voltage symmetry.When single-phase earthing took place, the ground connection phase voltage reduced, and perfected phase voltage and raise.According to detected voltage characteristic, can discern whether single-phase earthing has taken place in the small current neutral grounding system.When single-phase earthing takes place, earth point will be created in the current traveling wave of propagating in the system, and wherein, the initial polarity of traveling wave of the fault current of ground path is with to perfect circuit opposite, and the fault current initial row wave amplitude of ground path is greater than perfecting circuit.Thereby, can be through to the real-time collection and the detection of power-frequency voltage and current traveling wave, thus whether realization is to single phase ground fault has taken place in the small current neutral grounding system having discerned and having judged.
In technique scheme, preferably, said voltage collecting device comprises voltage transformer, and said current traveling wave harvester comprises zero sequence current mutual inductor.
In technique scheme, preferably, said power-frequency voltage is to utilize the three-phase voltage of the said bus that said voltage transformer collects and the open delta voltage of said voltage transformer.In this technical scheme, through voltage transformer power-frequency voltage is detected, simultaneously,, also can raise at the open delta voltage of voltage transformer if when breaking down, then can be with whether surpassing predetermined threshold value, as judging a condition that whether breaks down.
In technique scheme, preferably, said disturbance outlet judgment means specifically comprises: the amplitude comparing unit, and the current traveling wave of more said all outlets is selected the maximum outlet of amplitude; The polarity comparing unit, the current traveling wave of more said all outlets, the polarity of selecting current traveling wave is different from the outlet of the polarity of other current traveling waves; Disturbance outlet judging unit, with the outlet of being selected by said amplitude comparing unit and said polarity comparing unit simultaneously as said disturbance outlet.In this technical scheme,, will be created in the fault traveling wave of propagating in the system in the fault point when small current neutral grounding system generation single-phase earthing; At the wave impedance discontinuity point; Like the bus place of transformer station, catadioptric will take place in this fault traveling wave, and refraction is advanced in the outlet of other normal operations.Therefore, single-phase earthing takes place in small current neutral grounding system after, be installed in instrument transformer in all outlets of transformer station with this fault traveling wave of perception.The travelling wave signal that route selection utilizes among the present invention is the initial row ripple of fault generating; With regard to the current traveling wave in all outlets on being connected the same bus of transformer station; Current traveling wave in the outlet of generation single-phase earthing is to bus from line flows; Be sources of the current traveling wave that produces in other normal operation outlets, and the current traveling wave in the outlet of normal operation being for to flow to circuit from bus, is the part of the current traveling wave in the outlet of generation single-phase earthing; Therefore; The current traveling wave amplitude that takes place in the outlet of single-phase earthing is maximum, the current traveling wave in the outlet of normal operation, and it is opposite that the polarity of the current traveling wave in the outlet of current traveling wave polarity and normal operation in the outlet of single-phase earthing takes place.
In technique scheme; Preferably; Said earth fault judgment means specifically comprises: voltage comparison unit, and the more said open delta voltage and first predeterminated voltage, and in said three-phase voltage; Judge whether to exist a phase voltage to be lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage; The fault recognition unit; If the comparative result of said voltage comparison unit is: said open delta voltage is greater than said first predeterminated voltage; And in said three-phase voltage; Exist a phase voltage to be lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage, then confirm said small current neutral grounding system generation single phase ground fault.In this technical scheme, because when breaking down, open delta voltage can raise on the one hand, therefore it is set one first predeterminated voltage, as the threshold value of judging; On the other hand, in three-phase voltage, if there is a ground connection phase, then the voltage of this ground connection phase reduces, and other sound mutually then voltage raise, thereby can set second predeterminated voltage and the 3rd predeterminated voltage respectively as the threshold value of judging.
Through above technical scheme, can satisfy judgement to single-phase grounded malfunction in grounded system of low current, and fast, reliable, sensitive, insulation request selectively.
Description of drawings
Fig. 1 shows the flow chart of one-phase ground protection method according to an embodiment of the invention;
Fig. 2 shows the block diagram of one-phase ground protection system according to an embodiment of the invention;
Fig. 3 shows the particular flow sheet of one-phase ground protection according to an embodiment of the invention; And
Fig. 4 shows the particular flow sheet of one-phase ground protection according to an embodiment of the invention.
Embodiment
In order more to be expressly understood above-mentioned purpose of the present invention, feature and advantage, the present invention is further described in detail below in conjunction with accompanying drawing and embodiment.
Set forth a lot of details in the following description so that make much of the present invention, still, the present invention can also adopt other to be different from other modes described here and implement, and therefore, the present invention is not limited to the restriction of following disclosed specific embodiment.
Fig. 1 shows the flow chart of one-phase ground protection method according to an embodiment of the invention.
As shown in Figure 1; One-phase ground protection method according to an embodiment of the invention; Be used for single-phase grounded malfunction in grounded system of low current is judged and isolated; Comprise: step 102, the current traveling wave of all outlets that the power-frequency voltage of the bus of synchronous acquisition small current neutral grounding system and bus are corresponding in real time; Step 104 when in small current neutral grounding system, disturbance taking place, according to the current traveling wave of all outlets, is confirmed the disturbance outlet; Step 106 according to power-frequency voltage, confirms whether small current neutral grounding system single phase ground fault takes place; Step 108 when definite small current neutral grounding system generation single phase ground fault, confirms that the disturbance outlet is the fault outlet, sends trip command, the isolated fault outlet.In this technical scheme, when small current neutral grounding system normally moves, the three-phase voltage symmetry.When single-phase earthing took place, the ground connection phase voltage reduced, and perfected phase voltage and raise.According to detected voltage characteristic, can discern whether single-phase earthing has taken place in the small current neutral grounding system.When single-phase earthing takes place, earth point will be created in the current traveling wave of propagating in the system, and wherein, the initial polarity of traveling wave of the fault current of ground path is with to perfect circuit opposite, and the fault current initial row wave amplitude of ground path is greater than perfecting circuit.Thereby, can be through to the real-time collection and the detection of power-frequency voltage and current traveling wave, thus whether realization is to single phase ground fault has taken place in the small current neutral grounding system having discerned and having judged.
In technique scheme, in step 102, power-frequency voltage is to utilize the three-phase voltage of the bus that voltage transformer collects and the open delta voltage of voltage transformer.In this technical scheme, through voltage transformer power-frequency voltage is detected, simultaneously,, also can raise at the open delta voltage of voltage transformer if when breaking down, then can be with whether surpassing predetermined threshold value, as judging a condition that whether breaks down.
In technique scheme, in step 102, utilize zero sequence current mutual inductor to gather the current traveling wave of all outlets.
In technique scheme; In step 104; The process of confirming the disturbance outlet comprises: in the current traveling wave of all outlets, the outlet that the amplitude of selection current traveling wave is maximum and/or the polarity of current traveling wave are different from the outlet of the polarity of other current traveling waves, as the disturbance outlet.In this technical scheme,, will be created in the fault traveling wave of propagating in the system in the fault point when small current neutral grounding system generation single-phase earthing; At the wave impedance discontinuity point; Like the bus place of transformer station, catadioptric will take place in this fault traveling wave, and refraction is advanced in the outlet of other normal operations.Therefore, single-phase earthing takes place in small current neutral grounding system after, be installed in instrument transformer in all outlets of transformer station with this fault traveling wave of perception.The travelling wave signal that route selection utilizes among the present invention is the initial row ripple of fault generating; With regard to the current traveling wave in all outlets on being connected the same bus of transformer station; Current traveling wave in the outlet of generation single-phase earthing is to bus from line flows; Be sources of the current traveling wave that produces in other normal operation outlets, and the current traveling wave in the outlet of normal operation being for to flow to circuit from bus, is the part of the current traveling wave in the outlet of generation single-phase earthing; Therefore; The current traveling wave amplitude that takes place in the outlet of single-phase earthing is maximum, the current traveling wave in the outlet of normal operation, and it is opposite that the polarity of the current traveling wave in the outlet of current traveling wave polarity and normal operation in the outlet of single-phase earthing takes place.
In technique scheme; In step 106; The process of confirming small current neutral grounding system generation single phase ground fault comprises: if open delta voltage is greater than first predeterminated voltage, and in three-phase voltage, a phase voltage is lower than second predeterminated voltage; And other two phase voltages are higher than the 3rd predeterminated voltage, then confirm small current neutral grounding system generation single phase ground fault.In this technical scheme, because when breaking down, open delta voltage can raise on the one hand, therefore it is set one first predeterminated voltage, as the threshold value of judging; On the other hand, in three-phase voltage, if there is a ground connection phase, then the voltage of this ground connection phase reduces, and other sound mutually then voltage raise, thereby can set second predeterminated voltage and the 3rd predeterminated voltage respectively as the threshold value of judging.
Fig. 2 shows the block diagram of one-phase ground protection system according to an embodiment of the invention.
As shown in Figure 2; One-phase ground protection system 200 according to an embodiment of the invention; Be used for single-phase grounded malfunction in grounded system of low current is judged and isolated, comprise: voltage collecting device 202, the power-frequency voltage of the bus of synchronous acquisition small current neutral grounding system in real time; Current traveling wave harvester 204, the current traveling wave of all outlets that the synchronous acquisition bus is corresponding in real time; Disturbance outlet judgment means 206, when disturbance took place in small current neutral grounding system, the current traveling wave of all outlets of gathering according to current traveling wave harvester 204 was judged the disturbance outlet; Earth fault judgment means 208 according to the power-frequency voltage that voltage collecting device 202 is gathered, judges whether small current neutral grounding system single phase ground fault takes place; Spacer assembly 210 is judged under the situation of small current neutral grounding system generation single phase ground fault in earth fault judgment means 208, confirms that the disturbance outlet that disturbance outlet judgment means 206 is judged is the fault outlet, and sends trip command, the isolated fault outlet.In this technical scheme, when small current neutral grounding system normally moves, the three-phase voltage symmetry.When single-phase earthing took place, the ground connection phase voltage reduced, and perfected phase voltage and raise.According to detected voltage characteristic, can discern whether single-phase earthing has taken place in the small current neutral grounding system.When single-phase earthing takes place, earth point will be created in the current traveling wave of propagating in the system, and wherein, the initial polarity of traveling wave of the fault current of ground path is with to perfect circuit opposite, and the fault current initial row wave amplitude of ground path is greater than perfecting circuit.Thereby, can be through to the real-time collection and the detection of power-frequency voltage and current traveling wave, thus whether realization is to single phase ground fault has taken place in the small current neutral grounding system having discerned and having judged.
In technique scheme, voltage collecting device 202 comprises voltage transformer, and current traveling wave harvester 204 comprises zero sequence current mutual inductor.
In technique scheme, power-frequency voltage is to utilize the three-phase voltage of the bus that voltage transformer collects and the open delta voltage of voltage transformer.In this technical scheme, through voltage transformer power-frequency voltage is detected, simultaneously,, also can raise at the open delta voltage of voltage transformer if when breaking down, then can be with whether surpassing predetermined threshold value, as judging a condition that whether breaks down.
In technique scheme, disturbance outlet judgment means 206 specifically comprises: amplitude comparing unit 2060, and relatively the current traveling wave of all outlets is selected the maximum outlet of amplitude; Polarity comparing unit 2062, the current traveling wave of all outlets relatively, the polarity of selecting current traveling wave is different from the outlet of the polarity of other current traveling waves; Disturbance outlet judging unit 2064, with the outlet of being selected by amplitude comparing unit 2060 and polarity comparing unit 2062 simultaneously as the disturbance outlet.In this technical scheme,, will be created in the fault traveling wave of propagating in the system in the fault point when small current neutral grounding system generation single-phase earthing; At the wave impedance discontinuity point; Like the bus place of transformer station, catadioptric will take place in this fault traveling wave, and refraction is advanced in the outlet of other normal operations.Therefore, single-phase earthing takes place in small current neutral grounding system after, be installed in instrument transformer in all outlets of transformer station with this fault traveling wave of perception.The travelling wave signal that route selection utilizes among the present invention is the initial row ripple of fault generating; With regard to the current traveling wave in all outlets on being connected the same bus of transformer station; Current traveling wave in the outlet of generation single-phase earthing is to bus from line flows; Be sources of the current traveling wave that produces in other normal operation outlets, and the current traveling wave in the outlet of normal operation being for to flow to circuit from bus, is the part of the current traveling wave in the outlet of generation single-phase earthing; Therefore; The current traveling wave amplitude that takes place in the outlet of single-phase earthing is maximum, the current traveling wave in the outlet of normal operation, and it is opposite that the polarity of the current traveling wave in the outlet of current traveling wave polarity and normal operation in the outlet of single-phase earthing takes place.
In technique scheme; Earth fault judgment means 208 specifically comprises: voltage comparison unit 2080; Compare the open delta voltage and first predeterminated voltage; And in three-phase voltage, judge whether to exist a phase voltage to be lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage; Fault recognition unit 2082; If the comparative result of voltage comparison unit 2080 is: open delta voltage is greater than first predeterminated voltage; And in three-phase voltage; Exist a phase voltage to be lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage, then confirm small current neutral grounding system generation single phase ground fault.In this technical scheme, because when breaking down, open delta voltage can raise on the one hand, therefore it is set one first predeterminated voltage, as the threshold value of judging; On the other hand, in three-phase voltage, if there is a ground connection phase, then the voltage of this ground connection phase reduces, and other sound mutually then voltage raise, thereby can set second predeterminated voltage and the 3rd predeterminated voltage respectively as the threshold value of judging.
Fig. 3 shows the particular flow sheet of one-phase ground protection according to an embodiment of the invention.
As shown in Figure 3, the idiographic flow for one-phase ground protection according to an embodiment of the invention comprises:
Step 302, power-frequency voltage on the synchronous acquisition small current neutral grounding system bus and the current traveling wave in the outlet in real time.
Step 304, in when, in the small current neutral grounding system disturbance having taken place when, the outlet characteristic of popular ripple that powers on relatively, the outlet of disturbance takes place in identification.
Step 306 based on the power-frequency voltage that collects, judges whether single-phase earthing has taken place in the system.
Step 308 if single-phase earthing has taken place in the decision-making system, and identifies the outlet that disturbance takes place, and sends trip command, isolates ground path.
Behind the small current neutral grounding system generation single-phase earthing, the ground connection phase voltage reduces, and perfects phase voltage and raises.At earth point, single-phase earthing is created in the capable ripple of propagating in the system.At measurement point, the current transformer of installing on the line will detect capable ripple, and the current traveling wave polarity of ground path is with to perfect circuit opposite, and the current traveling wave amplitude of ground path is greater than perfecting circuit.
The operation principle of the one-phase ground protection method in the present embodiment:
When small current neutral grounding system normally moves, the three-phase voltage symmetry.When single-phase earthing took place, the ground connection phase voltage reduced, and perfected phase voltage and raise.According to detected voltage characteristic, can discern whether single-phase earthing has taken place in the small current neutral grounding system.When single-phase earthing takes place, earth point will be created in the current traveling wave of propagating in the system, and wherein, the initial polarity of traveling wave of the fault current of ground path is with to perfect circuit opposite, and the fault current initial row wave amplitude of ground path is greater than perfecting circuit.
When small current neutral grounding system generation single-phase earthing, will be created in the fault traveling wave of propagating in the system in the fault point, at the wave impedance discontinuity point, like the bus place of transformer station, catadioptric will take place in this fault traveling wave, and refraction is advanced in the outlet of other normal operations.Therefore, single-phase earthing takes place in small current neutral grounding system after, be installed in instrument transformer in all outlets of transformer station with this fault traveling wave of perception.The travelling wave signal that route selection utilizes among the present invention is the initial row ripple of fault generating; With regard to the current traveling wave in all outlets on being connected the same bus of transformer station; Current traveling wave in the outlet of generation single-phase earthing is to bus from line flows; Be sources of the current traveling wave that produces in other normal operation outlets, and the current traveling wave in the outlet of normal operation being for to flow to circuit from bus, is the part of the current traveling wave in the outlet of generation single-phase earthing; Therefore; The current traveling wave amplitude that takes place in the outlet of single-phase earthing is maximum, the current traveling wave in the outlet of normal operation, and it is opposite that the polarity of the current traveling wave in the outlet of current traveling wave polarity and normal operation in the outlet of single-phase earthing takes place.
Capable ripple in the small current neutral grounding system differs and establishes a capital because single-phase earthing causes, also maybe be because the killer switch operation causes that perhaps thunderbolt causes.But single-phase earthing must cause the variation of power-frequency voltage, and the ground connection phase voltage reduces, and perfects phase voltage and raises.Therefore, for accurately distinguish detected capable ripple on earth since single-phase earthing cause, still since other reasons cause, introduced the power-frequency voltage detection among the present invention, realize that accurately small current neutral grounding electric power system single-phase earthing judges.
Fig. 4 shows the particular flow sheet of one-phase ground protection according to an embodiment of the invention.
As shown in Figure 4, the idiographic flow of one-phase ground protection according to another embodiment of the invention comprises:
Disturbance has taken place if monitor in step 404 on the feeder line, each 128 capable wave datum of zero-sequence current of record before and after the ground connection are carried out four layers of wavelet transformation respectively, and the wavelet function is here selected a derived function of cubic B-spline function for use; Wavelet transformation result to the row wave datum extracts modulus maximum; Confirm the moment respectively from the corresponding modulus maximum of fault initial row ripple of zero sequence current mutual inductor.
Single-phase earthing has taken place in step 410 in decision-making system, and after having confirmed ground path, sends trip command, isolates ground path.
Traveling wave electric amount among the present invention refers to because the electromagnetic wave of in electric power system, propagating that the electric power system disturbance causes.Row wave-wave head can be regarded pulse signal as, has full range band component.The traveling wave electric amount that utilizes among the present invention is the capable wave-wave head signal with high frequency transient characteristic.
The present invention is based on the power-frequency voltage and the current traveling wave that measure, realize the single-phase earthing of small current earthing system protection.
The present invention can monitor the ruuning situation of small current neutral grounding system in real time, in time protects single-phase grounded malfunction in grounded system of low current, reduces electric power system fault, improves the power system power supply reliability, guarantees the power system safety and stability operation.
More than be described with reference to the accompanying drawings technical scheme of the present invention, considered that one-phase ground protection has higher requirement than single-phase grounding selecting.Therefore; The present invention is directed to one-phase ground protection; A kind of one-phase ground protection method and a kind of one-phase ground protection system are provided, thereby can have satisfied judgement single-phase grounded malfunction in grounded system of low current, and fast, reliable, sensitive, insulation request selectively.
The above is merely the preferred embodiments of the present invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. one-phase ground protection method is used for single-phase grounded malfunction in grounded system of low current is judged and isolated, and it is characterized in that, comprising:
Step 102, the current traveling wave of all outlets that the power-frequency voltage of the bus of the said small current neutral grounding system of synchronous acquisition and said bus are corresponding in real time;
Step 104 when in said small current neutral grounding system, disturbance taking place, according to the current traveling wave of said all outlets, is confirmed the disturbance outlet;
Step 106 according to said power-frequency voltage, confirms whether said small current neutral grounding system single phase ground fault takes place;
Step 108 when confirming said small current neutral grounding system generation single phase ground fault, confirms that said disturbance outlet is the fault outlet, sends trip command, isolates said fault outlet.
2. one-phase ground protection method according to claim 1 is characterized in that, in said step 102, said power-frequency voltage is to utilize the three-phase voltage of the said bus that voltage transformer collects and the open delta voltage of said voltage transformer.
3. one-phase ground protection method according to claim 1 and 2 is characterized in that, in said step 102, utilizes zero sequence current mutual inductor to gather the current traveling wave of said all outlets.
4. one-phase ground protection method according to claim 3 is characterized in that, in said step 104, the process of the said disturbance outlet of said affirmation comprises:
In the current traveling wave of said all outlets, the outlet that the amplitude of selection current traveling wave is maximum and/or the polarity of current traveling wave are different from the outlet of the polarity of other current traveling waves, as said disturbance outlet.
5. one-phase ground protection method according to claim 1 and 2 is characterized in that, in said step 106, confirms that the process of said small current neutral grounding system generation single phase ground fault comprises:
If said open delta voltage is greater than first predeterminated voltage, and in said three-phase voltage, a phase voltage is lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage, then confirms said small current neutral grounding system generation single phase ground fault.
6. one-phase ground protection system is used for single-phase grounded malfunction in grounded system of low current is judged and isolated, and it is characterized in that, comprising:
Voltage collecting device, the power-frequency voltage of the bus of the said small current neutral grounding system of synchronous acquisition in real time;
The current traveling wave harvester, the current traveling wave of all outlets that the said bus of synchronous acquisition is corresponding in real time;
Disturbance outlet judgment means, when disturbance took place in said small current neutral grounding system, the current traveling wave of said all outlets of gathering according to said current traveling wave harvester was judged the disturbance outlet;
The earth fault judgment means according to the said power-frequency voltage that said voltage collecting device is gathered, judges whether said small current neutral grounding system single phase ground fault takes place;
Spacer assembly; Judge in said earth fault judgment means under the situation of said small current neutral grounding system generation single phase ground fault; Confirm that the said disturbance outlet that said disturbance outlet judgment means is judged is the fault outlet, and send trip command, isolate said fault outlet.
7. one-phase ground protection according to claim 6 system it is characterized in that said voltage collecting device comprises voltage transformer, and said current traveling wave harvester comprises zero sequence current mutual inductor.
8. according to claim 6 or 7 described one-phase ground protection systems, it is characterized in that said power-frequency voltage is to utilize the three-phase voltage of the said bus that said voltage transformer collects and the open delta voltage of said voltage transformer.
9. according to claim 6 or 7 described one-phase ground protection systems, it is characterized in that said disturbance outlet judgment means specifically comprises:
The amplitude comparing unit, the current traveling wave of more said all outlets is selected the maximum outlet of amplitude;
The polarity comparing unit, the current traveling wave of more said all outlets, the polarity of selecting current traveling wave is different from the outlet of the polarity of other current traveling waves;
Disturbance outlet judging unit, with the outlet of being selected by said amplitude comparing unit and said polarity comparing unit simultaneously as said disturbance outlet.
10. one-phase ground protection according to claim 8 system is characterized in that said earth fault judgment means specifically comprises:
Voltage comparison unit, the more said open delta voltage and first predeterminated voltage, and in said three-phase voltage, judge whether to exist a phase voltage to be lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage;
The fault recognition unit; If the comparative result of said voltage comparison unit is: said open delta voltage is greater than said first predeterminated voltage; And in said three-phase voltage; Exist a phase voltage to be lower than second predeterminated voltage, and other two phase voltages are higher than the 3rd predeterminated voltage, then confirm said small current neutral grounding system generation single phase ground fault.
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