CN109725235A - A kind of flexible direct current power grid metallic return fault detection method - Google Patents
A kind of flexible direct current power grid metallic return fault detection method Download PDFInfo
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- CN109725235A CN109725235A CN201910112507.9A CN201910112507A CN109725235A CN 109725235 A CN109725235 A CN 109725235A CN 201910112507 A CN201910112507 A CN 201910112507A CN 109725235 A CN109725235 A CN 109725235A
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- metallic return
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The present invention discloses a kind of flexible direct current power grid metallic return fault detection method, and step is: in the state that metallic return is normal, being initially stored in original waveform；Driving pulse periodically is injected to metallic return, persistently calculates the different wave shape Dxy1 of current form and original waveform, when Dxy1 is less than different wave shape threshold Thrd1, updates reference waveform with current form；The different wave shape Dxy2 for persistently calculating current form and reference waveform, compared with different wave shape threshold Thrd2: if Dxy2 is not more than Thrd2, differentiating that metallic return is normal；If Dxy2 is greater than Thrd2, metallic return failure is differentiated, and calculate the ramification point of current form and reference waveform and the time difference dt1 of driving pulse, and calculate equivalent traveling wave speed v, position of failure point is finally calculated based on dt1 and v.The reliability and sensitivity of fault point reflected impulse detection can be improved in such method, is suitable for wave impedance discontinuous problem caused by different parallel lines on same tower forms, and improve the precision of the fault localization in the gradual situation of route velocity of wave.
Description
Technical field
The invention belongs to technical field of HVDC transmission, in particular to a kind of flexible direct current power grid metallic return failure inspection
Survey method.
Background technique
Current earthing pole addressing is more and more difficult in DC transmission system, therefore uses metal in flexible direct current engineering in the recent period
The mode of loop line replaces the earth to constitute circuit with metallic return, and metallic return and the direct current polar conductor same feeling are set up.Metal returns
The length of line and the length of DC line are consistent, after some time it is possible to reach tens Dao several hundred more kilometers.Metallic return short circuit or open-circuit fault
When, direct current system can all be run and cause security risk, it is therefore desirable to fault detection be carried out to metallic return, including monitored whether
It breaks down, and carries out fault localization.The method of operation of metallic return is similar with the ground electrode circuit method of operation, normal condition
Down without pressure without stream.Metallic return and polar conductor parallel lines on same tower, there is two kinds of single loop line parallel lines on same tower, double loop parallel lines on same tower feelings
Condition, metallic return has different wave impedance in the case of two kinds, single time, that there is wave impedance is discontinuous for double back line connection point
Problem.There are mainly two types of the practical approaches of ground electrode circuit fault detection at present: one is impedance methods, such as patent EP0360109
It is described, high-frequency signal is injected, impedance variations situation when failure is detected, can monitor whether that there are failures, but cannot achieve failure
Ranging；Another kind is pulse reflection method, fault detection system as shown in Figure 1, fault detection means injects driving pulse to route,
Fault monitoring and fault localization are realized by detection route reflected impulse.As shown in Fig. 2 (a), when route is normal, in wave impedance
Discontinuity point and line end can generate reflected impulse；As shown in Fig. 2 (b), when, there are when fault point, fault point can produce on route
Raw additional reflected impulse.
Traditional pulse reflection method principle is simple, and fault inspecting reflected impulse is only needed to can be realized fault detection, but
There are the following problems in engineer application:
(1) it since geographical and electromagnetic environmental impact, the line parameter circuit value along the line of route are simultaneously uneven, therefore is in route
Also many reflected impulses can be generated under normal condition, as shown in figure 3, these reflected impulses and fault point reflected impulse are difficult to area
Point；
(2) with the factors such as season, weather, conducting wire sag change, metallic return parameter can actually occur it is gradual, thus
It will lead to the variation of line equivalent velocity of wave, thus will lead to the error of traditional distance measuring method.
Therefore, it is necessary to try the reliability and sensitivity of raising fault point reflection configuration detection, and improve in route velocity of wave
The precision of fault localization in gradual situation.
Summary of the invention
The purpose of the present invention is to provide a kind of flexible direct current power grid metallic return fault detection method, by comparing sharp
Original waveform, reference waveform and the current form of pulse and its reflected impulse are encouraged, the reliable of fault point reflected impulse detection is improved
Property and sensitivity, be suitable for wave impedance discontinuous problem caused by different parallel lines on same tower forms, and improve slow in route velocity of wave
The precision of fault localization in the case of change.
In order to achieve the above objectives, solution of the invention is:
A kind of flexible direct current power grid metallic return fault detection method, includes the following steps:
Step 1, in the state that metallic return is normal, initially it is stored in original waveform；
Step 2, driving pulse periodically is injected to metallic return, and acquires current form；
Step 3, the different wave shape Dxy1 for persistently calculating current form and original waveform, when different wave shape Dxy1 is less than waveform
When divergence threshold Thrd1, reference waveform is updated with current form；
Step 4, persistently calculate current form and reference waveform different wave shape Dxy2, and with different wave shape threshold Thrd2
It is compared: if Dxy2 is not more than Thrd2, differentiating that metallic return is in normal condition；If Dxy2 is greater than Thrd2, metal is differentiated
Loop line is in malfunction, and goes to step 5；
Step 5, the ramification point of current form and reference waveform and the time difference dt1 of driving pulse are calculated, and according to reference
The time difference of the pulse of route end reflection and driving pulse calculates equivalent traveling wave speed v in waveform, finally based on time difference dt1 and
Traveling wave speed v calculates position of failure point.
After adopting the above scheme, the present invention is based on the basic principles of pulse reflection method, can be real by updating reference waveform
Tracking now slowly varying to metallic return parameter so as to improve the effect of comparison of wave shape, and can get accurate equivalent
Traveling wave speed.By comparing the difference of reference waveform and current form, it is uneven caused anti-to can solve metallic return parameter
Impulse disturbances problem is penetrated, the identification certainty and sensitivity of fault point reflected impulse can be improved.Therefore, the present invention can be mentioned effectively
The reliability and range accuracy of high metal line down detection.
Detailed description of the invention
Fig. 1 is metallic return fault detection system structure chart；
Fig. 2 is timing chart when metallic return is normal and when failure；
Fig. 3 is the reference waveform and current form comparison diagram of metallic return；
Fig. 4 is flow chart of the invention.
Specific embodiment
Below with reference to attached drawing, technical solution of the present invention and beneficial effect are described in detail.
The present invention provides a kind of flexible direct current power grid metallic return fault detection method, is based on time-domain pulse reflection principle,
As shown in Figure 1, periodically injecting driving pulse to metallic return from the fault detection means of metallic return first, and acquires and swash
Pulse and reflected pulse waveform are encouraged, saves original waveform, reference waveform and current form respectively, by comparing current form and original
The different wave shape of beginning waveform realizes that reference waveform updates, and by comparing the different wave shape of current form and reference waveform, realizes gold
Belong to line down differentiation and fault localization.
Original waveform, reference waveform and current form include overall process of the driving pulse to line end reflected impulse,
And the driving pulse waveform of three kinds of waveforms is identical, the alignment of driving pulse moment.Shown in reference waveform such as Fig. 2 (a), reflection is gold
State when category loop line is normal.When metallic return failure, it may appear that fault point reflected impulse, as shown in Fig. 2 (b).Compare Fig. 2
(a) with Fig. 2 (b), fault point reflected impulse can obviously be differentiated.
The Forming Mechanism of three kinds of waveforms is as follows:
Current form is the impulse waveform of state-of-the-art record, which reflects the current state of metallic return；
Original waveform is the impulse waveform that fault detection means initially saves in the trouble-free situation of metallic return, should
It is remained unchanged after waveform formation, unless receiving control command re-forms the waveform；
Reference waveform is the waveform automatically updated according to current form and original waveform, the difference of current form and original waveform
It is different be less than threshold value Thrd1 when, fault detection means with current form update reference waveform；In metallic return fault-free and metal
In the case that loop parameter is gradual, reference waveform can be continually updated.
Route caused by different wave shape threshold Thrd1 changes according to the metallic return parameter because of weather, weather, conducting wire sag
The slowly varying range setting of parameter, Thrd1 value range may be configured as 1%~3%.
The continuous updating of reference waveform allows fault detection means to track the slowly varying of line parameter circuit value in time, thus
Reflected impulse caused by metallic return parameter can be accurately reflected unevenly, this provides advantageous item for subsequent waveform comparison
Part, so as to clearly distinguish reflected pulse waveform caused by fault point, as shown in Figure 3.
Fault detection means compares current form and reference waveform in real time, when different wave shape is greater than threshold value Thrd2, sentences
Break down for metallic return, and according to the disagreement point moment of current form and reference waveform and driving pulse emission time when
Between difference dt1 calculate position of failure point.
The degree of caused different wave shape is true when different wave shape threshold Thrd2 is according to transition resistance R generation single-phase short circuit
Fixed, the value range of R is 100~1000 Ω, and the value range of Thrd2 may be configured as 1%~5%.
The calculation formula of position of failure point x is as follows:
X=0.5*dt1*v
In formula, v is traveling wave speed, and v is accurately determined according to reference waveform data, i.e. metallic return end in calculating reference waveform
The time difference dt2 of reflected impulse point and driving pulse emission time is held, and according to total track length L, traveling wave speed v can be obtained are as follows:
V=2*L/dt2
Different wave shape is calculated according to wave-form similarity coefficient, it may be assumed that
Wherein, Dxy is the different wave shape of curve x (k) and curve y (k),For curve x (k)
With the wave-form similarity coefficient of curve y (k)；
In formula, the calculation formula of Kxy, Kxx, Kyy are respectively as follows:
Wherein, N is the sampling number of whole section of waveform.
As shown in figure 4, implementation steps of the invention are as follows:
Step 41, in the state that metallic return is normal, initially it is stored in original waveform；
Step 42, fault detection means persistently calculates the different wave shape Dxy1 of current form and original waveform；
Step 43, when different wave shape Dxy1 is less than different wave shape threshold Thrd1, reference waveform is updated with current form；
Step 44, fault detection means persistently calculates the different wave shape Dxy2 of current form and reference waveform；
Step 45, compare different wave shape Dxy2 and different wave shape threshold Thrd2；
Step 46, when Dxy2 is not more than Thrd2, differentiate that metallic return is in normal condition；
Step 47, when Dxy2 is greater than Thrd2, differentiate that metallic return is in malfunction；
Step 48, when line fault, the ramification point of current form and reference waveform and the time difference of driving pulse are calculated
Dt1, and equivalent traveling wave speed v is calculated according to the time difference of the pulse of route end reflection and driving pulse in reference waveform, finally
Position of failure point is calculated based on time difference dt1 and equivalent traveling wave speed v.
Fault detection means periodical launch driving pulse, transmit cycle value range were a few tens of milliseconds by several seconds, preferably
Ground, can be by 1 second periodic emission driving pulse.Detection device continuously carries out step 42 to step 48 by the period, realizes metal
The lasting monitoring of line down.
The above examples only illustrate the technical idea of the present invention, and this does not limit the scope of protection of the present invention, all
According to the technical idea provided by the invention, any changes made on the basis of the technical scheme each falls within the scope of the present invention
Within.
Claims (7)
1. a kind of flexible direct current power grid metallic return fault detection method, it is characterised in that include the following steps:
Step 1, in the state that metallic return is normal, initially it is stored in original waveform；
Step 2, driving pulse periodically is injected to metallic return, and acquires current form；
Step 3, the different wave shape Dxy1 for persistently calculating current form and original waveform, when different wave shape Dxy1 is less than different wave shape
When threshold Thrd1, reference waveform is updated with current form；
Step 4, the different wave shape Dxy2 of current form and reference waveform is persistently calculated, and is carried out with different wave shape threshold Thrd2
Compare: if Dxy2 is not more than Thrd2, differentiating that metallic return is in normal condition；If Dxy2 is greater than Thrd2, metallic return is differentiated
In malfunction, and go to step 5；
Step 5, the ramification point of current form and reference waveform and the time difference dt1 of driving pulse are calculated, and according to reference waveform
The time difference of middle route end reflection pulse and driving pulse calculates equivalent traveling wave speed v, is finally based on time difference dt1 and traveling wave
Velocity of wave v calculates position of failure point.
2. a kind of flexible direct current power grid metallic return fault detection method as described in claim 1, it is characterised in that: the step
In rapid 2, the period for injecting driving pulse is 50 milliseconds~5 seconds.
3. a kind of flexible direct current power grid metallic return fault detection method as described in claim 1, it is characterised in that: the step
In rapid 3, the value range of different wave shape threshold Thrd1 is 1%~3%.
4. a kind of flexible direct current power grid metallic return fault detection method as described in claim 1, it is characterised in that: the step
In rapid 4, the value range of different wave shape threshold Thrd2 is 1%~5%.
5. a kind of flexible direct current power grid metallic return fault detection method as described in claim 1, it is characterised in that: the step
In rapid 5, the calculation formula of position of failure point x is as follows:
X=0.5*dt1*v
In formula, dt1 is the ramification point of current form and reference waveform and the time difference of driving pulse, and v is traveling wave speed.
6. a kind of flexible direct current power grid metallic return fault detection method as claimed in claim 5, it is characterised in that: the row
The calculation formula of wave velocity of wave v are as follows:
V=2*L/dt2
Wherein, L is total track length.
7. a kind of flexible direct current power grid metallic return fault detection method as described in claim 1, it is characterised in that: the step
Rapid 3 and step 4 in, the definition of different wave shape are as follows:
Wherein, Dxy is the different wave shape of curve x (k) and curve y (k)；
The calculation formula of Kxy, Kxx, Kyy are respectively as follows:
Wherein, N is the sampling number of whole section of waveform.
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Patent Citations (6)
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| CN1828324A (en) * | 2005-03-05 | 2006-09-06 | 淄博科汇电气有限公司 | Method for promoting testing reliability of cable obstacle |
| CN101566665A (en) * | 2009-06-09 | 2009-10-28 | 中国民航大学 | Plane cable fault locator based on time domain reflection |
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Application publication date: 20190507 |