CN102096024B - Method for searching direct-current earthing failure in electric power system - Google Patents
Method for searching direct-current earthing failure in electric power system Download PDFInfo
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- CN102096024B CN102096024B CN 201010594500 CN201010594500A CN102096024B CN 102096024 B CN102096024 B CN 102096024B CN 201010594500 CN201010594500 CN 201010594500 CN 201010594500 A CN201010594500 A CN 201010594500A CN 102096024 B CN102096024 B CN 102096024B
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Abstract
The invention provides a method for searching a direct-current earthing failure in an electric power system. The electric power system comprises a plurality of branch circuits and a first direct-current bus for supplying power to the plurality of branch circuits, wherein a first direct-current earthing failure detection device is arranged on the first direct-current bus. The method comprises the following steps of: a) providing a second direct-current bus and a second direct-current earthing failure detection device arranged on the second direct-current bus; b) determining branch circuits to be detected; and c) supplying power to the branch circuits to be detected jointly by utilizing the second direct-current bus and the first direct-current bus, and disconnecting the branch circuits to be detected from the first direct-current bus, wherein if the second direct-current earthing failure detection device indicates that a direct-current earthing failure occurs, the direct-current earthing failure occurs in the branch circuits. The method has the advantages of not influencing the running of the branch circuits during searching along with low cost and accurate failure positioning.
Description
Technical field
The present invention relates to the fault detect field of electric system, and relate in particular to a kind of method of searching the DC ground fault in the electric system.
Background technology
DC earthing is one of most common failure of electric system.When electric system generation one-point grounding fault (directly ground connection or insulation against ground resistance reduce); generally can not produce immediately the harmfulness consequence; but if 2 simultaneously ground connection occur; then may cause the misoperation of telltale, control loop and protective relaying device; cause circuit breaker trip or directly cause the direct supply short circuit, thereby cause serious power system accident.Therefore, do not allow on one point long-time running in the situation of DC earthing of electric system, must carry out continuous in-service monitoring to electric system, when any DC ground fault occurs, should get rid of it immediately, thereby stop the electric power system fault that causes because of DC ground fault.
Existing Method for Measuring Insulating Resistance comprises: balanced bridge method, unbalanced electric bridge, signal tracing method and Leakage Method etc.Yet; balanced bridge method and unbalanced electric bridge all can only detect the insulation status of whole electric system; when the branch road of DC ground fault occurring in the location; need disconnect successively being connected between each branch road and the dc bus; this can not carry out any operation therebetween so that the branch road of disconnection dc bus will move under the unprotect state.In addition, though signal tracing method and Leakage Method can be judged the branch road at DC ground fault place, but it is vulnerable to the impact that branch road electric capacity, sensor accuracy, looped network and ripple disturb, cause erroneous judgement, and complex structure, cost are higher, need set current transformer or direct current electricity leakage sensor for each branch road.
Therefore, this area is needed a kind of accurately DC ground fault lookup method of branch road operation, with low cost and localization of fault that do not affect badly.
Summary of the invention
Can affect branch road operation, location is inaccurate and cost is higher defective for overcoming existing positioning DC earth fault, spy of the present invention provides a kind of does not affect that branch road moves, with low cost and localization of fault DC ground fault lookup method accurately.
The invention provides a kind of method of searching the DC ground fault in the electric system, described electric system comprises a plurality of branch roads and first dc bus of powering to these a plurality of branch roads, be equipped with the first DC ground fault detection device on this first dc bus, the method comprises: step a): the second dc bus is provided and is equipped on the second DC ground fault detection device on this second dc bus; Step b): determine branch road to be detected; And step c): utilize described the second dc bus and described the first dc bus jointly to described branch road power supply to be detected, should disconnect from the first dc bus by branch road to be detected afterwards, if there is DC ground fault in described the second DC ground fault detection device indication, show that then there is DC ground fault in this branch road.
Wherein, described a plurality of branch roads can be connected mutually, and described the first dc bus can be connected in a plurality of branch roads one end that this is connected mutually, described step c) comprising: described the second dc bus is linked to each other with the other end of a plurality of branch roads of described mutual series connection; And with all branch roads of the other end from described branch road to be detected to a plurality of branch roads of this described mutual series connection in a plurality of branch roads of described mutual series connection from the first dc bus, if there is DC ground fault in the indication of the first DC ground fault detection device without DC ground fault and the indication of the second DC ground fault detection device, show that then there is DC ground fault in this branch road.
Wherein, if by execution in step c) determine that there is DC ground fault in described branch road to be detected, then determine another branch road to be detected, and execution in step c again).
Wherein, described step b) comprise that the branch road that mediates in a plurality of branch roads with described mutual series connection is as branch road to be detected.
Wherein, described the first and second DC earthing pick-up units can comprise insulation monitoring and warning device, universal electric meter or DC earthing detector etc.
The DC ground fault lookup method of the application of the invention can accurately be found out existing DC ground fault in the electric system, does not have the existing erroneous judgement situation of above signal tracing method and Leakage Method.And in search procedure, by powering with the second dc bus, can guarantee that all branch roads in the electric system all can run without interruption, improved the security of whole electric system.
In addition, the equipment that DC ground fault lookup method of the present invention adopts is simple, for itself being for the electric system of two dc bus partition runnings, each branch road loop operation of subordinate, only need set up a direct current ground fault detection device, just can realize that DC ground fault accurately searches, with low cost.
Description of drawings
Fig. 1 is the process flow diagram of searching the method for DC ground fault provided by the invention;
Fig. 2 is the structural representation of method of the searching DC ground fault provided by the invention electric system that can be applied to; And
Fig. 3 be method of searching DC ground fault provided by the invention can be applied to the structural representation of another electric system.
Embodiment
For allow above and other purpose of the present invention, feature and advantage can be more obvious, hereinafter will cooperate appended diagram, be described in detail below.In addition, in explanation of the present invention, identical member is with identical symbolic representation, in this close chat first bright.
Fig. 1 is the process flow diagram of searching the method for DC ground fault provided by the invention.As shown in Figure 1, the invention provides a kind of method of searching the DC ground fault in the electric system, described electric system comprises a plurality of branch roads and first dc bus of powering to these a plurality of branch roads, be equipped with the first DC ground fault detection device on this first dc bus, the method comprises: step a): the second dc bus is provided and is equipped on the second DC ground fault detection device on this second dc bus; Step b): determine branch road to be detected; And step c): utilize described the second dc bus and described the first dc bus jointly to described branch road power supply to be detected, should disconnect from the first dc bus by branch road to be detected afterwards, if there is DC ground fault in described the second DC ground fault detection device indication, show that then there is DC ground fault in this branch road.
Wherein, if by execution in step c) determine that there is DC ground fault in described branch road to be detected, then determine another branch road to be detected, and execution in step c again).
Fig. 2 is the structural representation of method of the searching DC ground fault provided by the invention electric system that can be applied to.As shown in Figure 2, this electric system comprises that described electric system comprises the first DC ground fault detection device 110, the second DC ground fault detection device 120, the first dc bus I, the second dc bus II, K switch 0, K switch 11, K switch 12, ..., K switch 1n, branch road L1, branch road L2, ... .., branch road Ln and K switch 21, K switch 22, ..., K switch 2n (wherein, n＞1, and n is integer), branch road L1, branch road L2, ... .., branch road Ln is respectively through K switch 11, K switch 12, ..., K switch 1n and link to each other branch road L1 with the first dc bus I, branch road L2, ... .., branch road Ln is respectively through K switch 21, K switch 22, ..., K switch 2n and linking to each other with the second dc bus II.Described the first DC ground fault detection device 110 is electrically connected with the first dc bus I, whether has DC ground fault in the branch road of powering for detection of this first dc bus I; The second DC ground fault detection device 120 is electrically connected with the second dc bus II, whether has DC ground fault in the branch road of powering for detection of this second dc bus II.
Under normal circumstances, K switch 11, K switch 12 ..., K switch 1n is closed, K switch 0, K switch 21, K switch 22 ..., K switch 2n disconnects, branch road L1, branch road L2 ... .., branch road Ln power by the first dc bus I.
When having DC ground fault in the branch road that the first DC ground fault detection device 110 indications the first dc bus I powers, but Closing Switch K21 (making the second dc bus II to this branch road L1 power supply), cut-off switch K11 (this branch road L1 is disconnected from the first dc bus I) afterwards, if this moment, there was DC ground fault in 120 indications of the second DC ground fault detection device, then show among the branch road L1 to have DC ground fault.Mode is carried out DC ground fault to other branch roads in the electric system and is detected thus.
Described a plurality of branch road can be connected mutually, and described the first dc bus can be connected in a plurality of branch roads one end that this is connected mutually, described step c) comprising: described the second dc bus is linked to each other with the other end of a plurality of branch roads of described mutual series connection; And with all branch roads of the other end from described branch road to be detected to a plurality of branch roads of this described mutual series connection in a plurality of branch roads of described mutual series connection from the first dc bus, if there is DC ground fault in the indication of the first DC ground fault detection device without DC ground fault and the indication of the second DC ground fault detection device, show that then there is DC ground fault in this branch road.
Preferably, described step b) comprise that the branch road that mediates in a plurality of branch roads with described mutual series connection is as branch road to be detected.Progressively dwindle seek scope with this, improve search efficiency.
Fig. 3 is the structural representation of method of searching DC ground fault provided by the invention another electric system that can be applied to.As shown in Figure 3, this electric system comprises: the first DC ground fault detection device 110, the second DC ground fault detection device 120, the first dc bus I, the second dc bus II, K switch 0, K switch 30, K switch 31, K switch 32, ..., K switch 3n, branch road L1, branch road L2, ... .., branch road Ln (wherein, n＞1, and n is integer), the first dc bus I, branch road L1, branch road L2, ... .., branch road Ln and the second dc bus II are respectively via K switch 30, K switch 31, K switch 32, ..., K switch 3n and K switch 0 are in series, and consist of a direct current loop.Described the first DC ground fault detection device 110 is electrically connected with the first dc bus I, whether has DC ground fault in the branch road of powering for detection of this first dc bus I; The second DC ground fault detection device 120 is electrically connected with the second dc bus II, whether has DC ground fault in the branch road of powering for detection of this second dc bus II.
Under normal circumstances, K switch 30, K switch 31, K switch 32 ... .., K switch 1 (n-1) closure, K switch 0, K switch 1n disconnect, branch road L1, branch road L2 ... .., branch road Ln power by the first dc bus I.When having DC ground fault in the branch road that the first DC ground fault detection device 110 indications the first dc bus I powers, but Closing Switch K1n (at this moment, there is DC ground fault in the branch road that the second DC ground fault detection device 120 also can indicate the second dc bus II to power), cut-off switch K31 afterwards, if this moment, there was not DC ground fault in 110 indications of the first DC ground fault detection device, and the second DC ground fault detection device 120 still indicates and has DC ground fault, shows that then DC ground fault is present in branch road L2, ..., among the branch road Ln.Afterwards, Closing Switch K31, cut-off switch K32, if this moment, there was DC ground fault in 110 indications of the first DC ground fault detection device, and there is not DC ground fault in 120 indications of the second DC ground fault detection device, show that then DC ground fault is present among the branch road L2, put line operate into otherwise continue to split, follow-up branch road is searched.
Preferably, Closing Switch K3n at first, the switch of disconnection middle branch (such as, K switch 3 (n/2)), if this moment, there was DC ground fault in 110 indications of the first DC ground fault detection device, and the second DC ground fault detection device 120 shows and does not have DC ground fault, then show DC ground fault be present in branch road L1, L2 ..., L (n/2).Afterwards, Closing Switch K1 (n/2), cut-off switch K1 (n/4) continues to dwindle fault coverage.By this, by constantly dwindling fault coverage, can improve the search efficiency of DC ground fault.
In sum, the present invention is existing DC ground fault in the electric system accurately, and during searching, can guarantee that all branch roads in the electric system all can run without interruption, and has improved the security of whole electric system.In addition, the equipment that DC ground fault lookup method of the present invention adopts is simple, for itself being for the electric system of two dc bus partition runnings, each branch road loop operation of subordinate, only need set up a direct current ground fault detection device, just can realize that DC ground fault accurately searches, with low cost.
Although the present invention is disclosed by above-described embodiment, yet above-described embodiment is not to limit the present invention, any the technical staff in the technical field of the invention without departing from the spirit and scope of the present invention, should do various changes and modification.Therefore protection scope of the present invention should be as the criterion with the scope that appended claims was defined.
Claims (5)
1. method of searching the DC ground fault in the electric system, described electric system comprises a plurality of branch roads and first dc bus of powering to these a plurality of branch roads, be equipped with the first DC ground fault detection device on this first dc bus, it is characterized in that, the method comprises:
Step a): the second dc bus is provided and is equipped on the second DC ground fault detection device on this second dc bus; Wherein, when described electric system normally moves, described the second dc bus no-load running;
Step b): when described electric system generation earth fault, determine branch road to be detected; And
Step c): utilize described the second dc bus and described the first dc bus jointly to described branch road power supply to be detected, should disconnect from the first dc bus by branch road to be detected afterwards, if there is DC ground fault in described the second DC ground fault detection device indication, show that then there is DC ground fault in this branch road.
2. method according to claim 1, wherein, described a plurality of branch roads are connected mutually, and described the first dc bus is connected in a plurality of branch roads one end that this is connected mutually, and described step c) comprises:
Described the second dc bus is linked to each other with the other end of a plurality of branch roads of described mutual series connection; And
All branch roads of the other end of a plurality of branch roads from described branch road to be detected to this described mutual series connection in a plurality of branch roads of described mutual series connection are disconnected from the first dc bus, if there is DC ground fault in the indication of the first DC ground fault detection device without DC ground fault and the indication of the second DC ground fault detection device, show that then there is DC ground fault in this branch road.
3. method according to claim 1 and 2 is wherein, if by execution in step c) determine that there is DC ground fault in described branch road to be detected, then determine another branch road to be detected, and execution in step c again).
4. method according to claim 2, wherein, described step b) comprises that the branch road that mediates in a plurality of branch roads with described mutual series connection is as branch road to be detected.
5. method according to claim 1, wherein, described the first and second DC ground fault detection devices comprise insulation monitoring and warning device, universal electric meter or DC earthing detector.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201010594500 CN102096024B (en) | 2010-12-17 | 2010-12-17 | Method for searching direct-current earthing failure in electric power system |
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| CN 201010594500 CN102096024B (en) | 2010-12-17 | 2010-12-17 | Method for searching direct-current earthing failure in electric power system |
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| CN102096024B true CN102096024B (en) | 2013-05-01 |
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| US7301739B2 (en) * | 2005-10-12 | 2007-11-27 | Chevron U.S.A. Inc. | Ground-fault circuit-interrupter system for three-phase electrical power systems |
| CN101382577B (en) * | 2008-10-24 | 2010-12-01 | 华北电力大学 | Single-phase earth fault positioning device for electrical power distribution network |
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