CN104698355A - On-line diagnosing method of high-voltage cable partial discharge - Google Patents
On-line diagnosing method of high-voltage cable partial discharge Download PDFInfo
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- CN104698355A CN104698355A CN201510124414.XA CN201510124414A CN104698355A CN 104698355 A CN104698355 A CN 104698355A CN 201510124414 A CN201510124414 A CN 201510124414A CN 104698355 A CN104698355 A CN 104698355A
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Abstract
The purpose of the invention is to increase the efficiency of discovering and resolving partial discharge faults of high-voltage cables. Therefore, a technical scheme as follows is provided: an on-line diagnosing method of a high-voltage cable partial discharge comprising the steps of (1) detecting discharge signals of a plurality of nodes on the high-voltage cable; (2) pre-processing the plurality of discharge signals; (3) generating discharge spectra of the discharge signals; (4) judging a type of a partial discharge fault based on the result of differencing the discharge spectrum of each node with the discharge spectrum of the adjacent next node; and (5) determining the position of the partial discharge based on the result of differencing and the result of judging the type of the partial discharge. With the on-line diagnosing method of the high-voltage cable partial discharge, the partial discharge fault can be monitored at the real time based on the inherent nodes of the high-voltage cable, thereby increasing the efficiency of discovering the partial discharge fault of the high-voltage cable greatly.
Description
Technical field
The present invention relates to electric fault detection technique field, more specifically, relate to a kind of high-tension cable shelf depreciation inline diagnosis method.
Background technology
High-tension cable is the important component part of electric system.Along with the development of high pressure and extra high voltage network, power cable is applied more and more widely because its distinctive technological merit obtains.Cable is in operational process, and internal field's stress that can cause due to factors such as the accumulation of space charge under the impurity of inside, semiconductor layer projection, voltage effect is concentrated, and produces shelf depreciation, the safe operation of cable is affected.Therefore, the shelf depreciation insulated by detection streamer, can judge the aging conditions of cable insulation effectively, and this runs significant for power cable line long-term stability.
The electric field that each region of insulator of high-tension cable is born is generally uneven, and the factor causing electric field uneven mainly contains: 1. the electrode system of electrical equipment is asymmetric, as plate, right cylinder etc.At the high-voltage terminal end of transformer, the position electric fields such as the end of cable are more concentrated, easily first produce electric discharge.2. medium is uneven, as various complex media: gas solids combination, liquid-solid combination etc.Under alternating electric field, the electric field intensity in medium and its specific inductive capacity are inversely proportional to, and in the medium that therefore specific inductive capacity is little, electric field intensity is high, easily discharges.3. bubble or other impurity is contained in insulator.The relative dielectric constant of gas is close to 1, all large than it more than 1 times of the relative dielectric constant of various solid, liquid medium, and the breakdown field strength of solid, liquid medium is generally than several times to tens times greatly of gas medium, therefore having bubble to exist in insulator is the most common reason producing shelf depreciation.Bubble in insulator may be residual lower in manufacture course of products, also may be on the interface of different materials, to have occurred crack due to expanding with heat and contract with cold in product runs, or aging and decomposite gas by insulating material.4. in addition, if there is the metallic object of electric potential floating to exist in high field intensity, also very high field intensity can be induced at its edge; In each junction of electrical equipment, if contact bad, also high field intensity can be produced between two contacts that distance is very small; These all may cause shelf depreciation.
At present, various countries adopt different principles to carry out the separation method of the collection of each characteristic quantity of cable partial discharge signal and contrast, Partial discharge signal and interference model.But these methods are all unfavorable for type and the location of on-line monitoring partial discharges fault, cannot Timeliness coverage dealing with problems.
Summary of the invention
The object of the invention is the discovery and the solution efficiency that improve high-tension cable partial discharges fault.For this reason, the invention provides following technical scheme:
A kind of high-tension cable shelf depreciation inline diagnosis method, comprises the steps:
(1) multiple node discharge signal separately on high-tension cable is detected;
(2) multiple discharge signal described in pre-service;
(3) the electric discharge collection of illustrative plates of described discharge signal is generated;
(4) along high-tension cable electric power transfer direction, the electric discharge collection of illustrative plates of each node and the electric discharge collection of illustrative plates of the next node adjacent with it are carried out difference, if the difference result obtained is within predetermined threshold value, then judges that partial discharges fault does not appear in this node; If the difference result obtained is greater than predetermined threshold value, then carry out the judgement of partial discharges fault type;
(5) according to the judged result of difference result and partial discharges fault type, the position of shelf depreciation is determined.
Further, described step (1) comprising: synchronous acquisition on each node of the three-phase line of high-tension cable also preserves partial discharge pulse's signal of the high voltage cable insulation defect of frequency between 400kHz ~ 20MHz.
Further, described step (5) comprising: determine same partial discharges fault type and the node of continuous distribution according to the difference result of all nodes, and wherein the node of discharge signal amplitude maximum is exactly the partial discharges fault node of this fault type.
Further, gathered by the discharge signal of current transformer to graceful cable.
Further, described high-tension cable is provided with Luo-coil.
Further, current transformer utilizes the shelf depreciation of pulse current method to high-tension cable to be measured to detect.
Further, the ambient noise signal in 3PARD algorithm separation discharge signal is utilized.
Further, described electric discharge collection of illustrative plates is the oval spectrogram of electric discharge.
The invention has the beneficial effects as follows: partial discharges fault can be monitored in real time based on the intrinsic node of high-tension cable, greatly improve the discovery efficiency of high-tension cable partial discharges fault.In addition, the localization method based on intrinsic node also saves the time of searching spent by high-tension cable partial discharges fault position, enhances the stability of high-tension cable electric power transfer.
Accompanying drawing explanation
Fig. 1 shows the FB(flow block) according to high-tension cable shelf depreciation inline diagnosis method of the present invention.
Embodiment
As shown in Figure 1, high-tension cable shelf depreciation inline diagnosis method comprises the steps:
(1) multiple node discharge signal separately on high-tension cable is detected; Each described node is existing transformer node or have any node of monitoring function on high-tension cable, or the physical node of other form any; Also can be lay the section that region or geographical environment and/or physical environment divide and the node arranged with high-tension cable.High-tension cable comprises threephase cable and is provided with Luo-coil, and the every of described threephase cable all installs signal transducer mutually, carries out local discharge signal detection mutually to each simultaneously.During collection, synchronous acquisition on each node of the three-phase line of high-tension cable also preserves partial discharge pulse's signal of the high voltage cable insulation defect of frequency between 400kHz ~ 20MHz.
Current transformer utilizes the shelf depreciation of pulse current method to high-tension cable to be measured to detect.Signal transducer adopts pulse current method to measure the local discharge signal of high-tension cable; Pulse current method be study the earliest, a kind of most widely used method, IEC (International Electrotechnical Commission) has formulated special standard to this; By the pulse current waveform parameter that the measurement of broadband waveform measurement instrument obtains, can be used for characterizing the different stages of development of different discharge type and electric discharge.
(2) described multiple discharge signal is amplified, filtering and A/D conversion;
(3) the electric discharge collection of illustrative plates of described discharge signal is generated;
According to one embodiment of present invention, 3PARD (three-phase magnitude relation figure) is adopted to be separated the ground unrest in discharge signal, after ground unrest separation is carried out to local discharge signal, the information such as the peak value of discharge signal, mean value, discharge frequency, discharge current or phase diagram can be obtained.According to corresponding information, thus signal-voltage curve can be generated, signal-time curve or voltage-time curve, and starting potential, extinction voltage, the discharge capacity information in each moment that can obtain shelf depreciation.
Adopt this 3PARD to be separated ground unrest, local discharge signal can be separated with interference, also different offices can be separated by the signal put a little, thus identify the phenomenon of multiple spot electric discharge; Utilize the magnitude relation of the signal of triple channel synchro measure, can also tell easily signal come from which phase cable can joint, to effectively prevent in cable grounding casing cross interconnected row to the impact of local discharge test.
According to another embodiment of the invention, described electric discharge collection of illustrative plates is the oval spectrogram of electric discharge.
(4) along high-tension cable electric power transfer direction, the electric discharge collection of illustrative plates of the electric discharge collection of illustrative plates of each node and the next node adjacent with it is carried out difference, the difference result of the collection of illustrative plates that discharges represents its difference each other.When other amplitude of being on duty does not exceed the amplitude of the difference result between the node that detects under normal circumstances, then judge that partial discharges fault does not appear in this node; Otherwise, the rule judgment partial discharges fault type according to below:
1, insulate excellent and without external interference, without shelf depreciation collection of illustrative plates;
Cable insulation is excellent, and during without external interference, its measured waveform is very clean, and in the 1-4 quadrant of plane coordinate system, signal is very well-balanced.
2, internal air gap electric discharge collection of illustrative plates
When discharging in high-voltage cable insulating body internal air gap, in air gap, the exchange of electric charge and accumulation there is no method at present and directly measure, but the change of this electric charge, the change of the upper electric charge of insulator two end electrodes (conductor) will inevitably be reflected to.Relation between both, can be analyzed by equivalent electrical circuit.
The electric discharge of usual media interior air gap is identical substantially in positive and negative two half cycles, and oscillography screen can see that the figure of positive-negative half-cycle discharge pulse is symmetrical substantially.
Can draw from the actual electric discharge figure recorded in a large number, electric discharge does not appear in the one section of phase place crossing peak value of trial voltage, and the size of each electric discharge, the i.e. height of pulse unequal, and mostly electric discharge is in the phase place of the rising part appearing at trial voltage amplitude absolute value, namely at 1 of plane coordinate system, on 3 quadrants, only when discharging very violent, just can expand in the phase place of absolute value of voltage sloping portion, namely at 2 of plane coordinate system, on 4 quadrants, this may be discharge owing to often there is multiple bubble in actual test product simultaneously, or only have an air pocket, but each electric discharge is not that whole bubble area is all discharged, and be a part wherein, obviously the electric charge of each electric discharge is not necessarily identical, in addition also may when back discharge, not necessarily can neutralize the electric charge of original accumulation, but positive and negative charge is all accumulated near walls, therefore, produce the surface-discharge along walls.
3, inner impurity electric discharge
High-voltage cable insulating body is placed copper metal powder end granule foreign, the cable partial discharge feature that impurity causes.The presence or absence of this kind of defect and type judge, can analyze by contrasting with collection of illustrative plates.
4, corona discharge
Corona discharge occurs in around conductor when being gas entirely, or the liquid existed in the gas space, solid objects all from produce electric discharge conductor enough away from, molecule in gas moves freely, the charging point that electric discharge produces also can not be fixed on a certain fixed position in space, and therefore discharge process is different containing alveolate discharge process from above-mentioned solid or fluid insulation.For the electrode system for plate, near needle point, field intensity is the highest, when the field intensity that impressed voltage rises to this place reaches the breakdown field strength of gas, just discharge near needle point, due to electrode easy electron emission when negative polarity, the secondary of positive ion bombardment negative electrode generation simultaneously, electric discharge is always first occurred when needle point is negative polarity, at this moment positive ion, shift to needlepoint electrode very soon and compound, electronics is shifting to plate electrode process, be attached to neutral molecule and become negative ion, the speed of negative ion migration is slower, numerous negative ions in-between the electrodes, electric field intensity near needle point is reduced, so electric discharge suspends.Afterwards, along with negative ion shifts to plate electrode, or impressed voltage rises, and the electric field near needle point is elevated to again the breakdown field strength of gas, so there is again second time electric discharge.Like this, the discharge pulse of corona just appears near impressed voltage negative half period 90 degree of phase places, is almost be symmetrical in 90 degree, and the discharge pulse of appearance such as is almost at the amplitude, equally spaced.Along with the raising of voltage, discharge magnitude is almost constant, only has number of times to increase.When voltage is enough high, also there will be the large electric discharge of a small amount of amplitude at positive half cycle.
(5) according to the judged result of difference result and partial discharges fault type, the position of shelf depreciation is determined.Determine same partial discharges fault type and the node of continuous distribution according to the difference result of all nodes, wherein the node of discharge signal amplitude maximum is exactly the partial discharges fault node of this fault type.For one section of high-tension cable, there is more than one of the position possibility of shelf depreciation.Adopt method of the present invention can obtain the position of each partial discharges fault point, thus improve the accuracy of inline diagnosis.
The above embodiment only have expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.
Claims (8)
1. a high-tension cable shelf depreciation inline diagnosis method, is characterized in that, comprise the steps:
(1) multiple node discharge signal separately on high-tension cable is detected;
(2) multiple discharge signal described in pre-service;
(3) the electric discharge collection of illustrative plates of described discharge signal is generated;
(4) along high-tension cable electric power transfer direction, the electric discharge collection of illustrative plates of each node and the electric discharge collection of illustrative plates of the next node adjacent with it are carried out difference, if the difference result obtained is within predetermined threshold value, then judges that partial discharges fault does not appear in this node; If the difference result obtained is greater than predetermined threshold value, then carry out the judgement of partial discharges fault type;
(5) according to the judged result of difference result and partial discharges fault type, the position of shelf depreciation is determined.
2. high-tension cable shelf depreciation inline diagnosis method according to claim 1, it is characterized in that, described step (1) comprising: synchronous acquisition on each node of the three-phase line of high-tension cable also preserves partial discharge pulse's signal of the high voltage cable insulation defect of frequency between 400kHz ~ 20MHz.
3. high-tension cable shelf depreciation inline diagnosis method according to claim 1, it is characterized in that, described step (5) comprising: determine same partial discharges fault type and the node of continuous distribution according to the difference result of all nodes, and wherein the node of discharge signal amplitude maximum is exactly the partial discharges fault node of this fault type.
4. high-tension cable shelf depreciation inline diagnosis method according to claim 2, be is characterized in that, gathered by the discharge signal of current transformer to graceful cable.
5. high-tension cable shelf depreciation inline diagnosis method according to claim 4, is characterized in that, described high-tension cable is provided with Luo-coil.
6. high-tension cable shelf depreciation inline diagnosis method according to claim 5, is characterized in that, current transformer utilizes the shelf depreciation of pulse current method to high-tension cable to be measured to detect.
7. high-tension cable shelf depreciation inline diagnosis method according to claim 1, is characterized in that, utilizes the ambient noise signal in 3PARD algorithm separation discharge signal.
8. high-tension cable shelf depreciation inline diagnosis method according to claim 1, is characterized in that, described electric discharge collection of illustrative plates is the oval spectrogram of electric discharge.
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Cited By (5)
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| WO2017029415A1 (en) * | 2015-08-20 | 2017-02-23 | Bombardier Transportation Gmbh | Method and test setup for measuring partial discharges in plug connections in a rail vehicle |
| CN109633385A (en) * | 2018-12-03 | 2019-04-16 | 珠海华网科技有限责任公司 | A kind of method that noise and electric discharge are distinguished in the on-line monitoring of cable of HFCT |
| CN109917235A (en) * | 2019-04-22 | 2019-06-21 | 广东电网有限责任公司 | A kind of cable slack layer electric conductivity defect inspection method |
| CN111044857A (en) * | 2019-12-13 | 2020-04-21 | 北京信息职业技术学院 | Radio frequency monitoring method and device for multiple partial discharge sources |
| CN112305370A (en) * | 2019-08-01 | 2021-02-02 | 中国石油化工股份有限公司 | Single-core XLPE power cable fault early warning method and device |
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