CN112763851B - Method for rapidly screening ablation hidden danger cable section based on inner surface area of corrugated sheath - Google Patents
Method for rapidly screening ablation hidden danger cable section based on inner surface area of corrugated sheath Download PDFInfo
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Abstract
The invention relates to a method for quickly screening ablation hidden danger cable sections based on the inner surface area of a corrugated sheath, which is technically characterized by comprising the following steps of: according to the inner side surface area of the corrugated sheath in the single corrugated pitch, the inner side surface area of the corrugated sheath of the high-voltage power cable is approximately calculated; according to the surface area of the inner side of the wrinkle sheath of the high-voltage power cable, the screening threshold of the potential ablation hazard cable section of the buffer layer is calculated by using the contact ratio of the fault cable section recorded in historical data, and the potential ablation hazard cable section of the buffer layer is rapidly screened through the screening threshold of the potential ablation hazard cable section of the buffer layer. The method is reasonable in design, the function of rapidly screening the cable section with the ablation hidden danger of the buffer layer is realized by approximately calculating the surface area of the inner side of the corrugated sheath of the high-voltage power cable, the method can be used for performing performance evaluation on the condition that the size of the corrugated sheath of the high-voltage power cable is matched with the size of the buffer layer, and provides a list of the cable section with the ablation hidden danger of the buffer layer of cables in stock, so that reference is provided for operation and maintenance of the high-voltage power cable.
Description
Technical Field
The invention belongs to the technical field of high voltage and insulation, and particularly relates to a method for quickly screening ablation hidden danger cable sections based on the inner surface area of a corrugated sheath.
Background
In recent years, the number of faults caused by ablation of a buffer layer of a high-voltage power cable is gradually increased, and the ablation hidden danger of the buffer layer becomes one of important hidden dangers threatening the safety of a power grid. At present, a screening method for a cable section with hidden danger of buffer layer ablation of a high-voltage power cable is still very primary, and a method for summarizing a cable supplier list with faults of the type and listing other cables which are not faulty in the list as hidden danger cables is generally adopted. This approach usually results in a number of high voltage power cables from several suppliers requiring technical modification or replacement, but other supplier products are completely non-hazardous. The screening method does not take technical information of specific cables into account, so that the hidden dangers of cable products of screened supplier lists are easily overestimated on one hand, and the risks of cable products of other suppliers are easily ignored on the other hand. Therefore, a method for screening ablation risks by combining cable information needs to be developed.
Ablation of a water-blocking buffer layer is generally accompanied by the following two phenomena: (1) the water-blocking buffer layer is affected with damp; (2) The corrugated sheath, buffer layer and insulation shield material are relatively weak in electrical connection. The former can be prevented by enhancing management and control in the cable production stage and the construction stage. The latter is still difficult due to the short time to find a replacement for the combination corrugated aluminum sheath-water-blocking buffer-insulation shielding material. Therefore, on the premise that the material cannot be changed, under the condition that the buffer belt is tightly wrapped on the insulation shielding layer, the contact area between the corrugated sheath and the buffer layer becomes key information for determining the electrical connection between the corrugated sheath and the insulation shielding layer, and a method for screening the ablation hidden danger of the buffer layer can be developed accordingly.
Neglecting the influence caused by cable bending, the method for visually estimating the contact area (hereinafter referred to as contact area) between the corrugated sheath and the buffer layer is to take the cylindrical area formed by the circle outside the buffer layer coated on the cable along the axial direction of the cable or the cylindrical area formed by the circle at the position of a wave trough inside the corrugated sheath along the axial direction of the cable as the estimated value of the contact area. The premise of the method is that the corrugated sheath is completely and tightly contacted with the buffer layer, and the method is not in accordance with the actual engineering and brings great errors when the electrical connection condition is analyzed. Therefore, the contact area, a key technical parameter, still lacks an effective calculation means, and the solution of the problem mainly has the following challenges:
(1) Power cable suppliers commonly use metal corrugated production lines for corrugated sheath production. The technical parameters of the sheath wrinkles are controlled through two production parameters of the wrinkle pitch and the wrinkle depth. This approach does not directly determine the shape parameters of smooth wrinkles, typical of the radius of curvature. In addition, the contact with the buffer layer in the axial direction of the cable is generally discontinuous due to the presence of peaks and valleys in the corrugated jacket. These problems present difficulties in mathematical modeling and calculation of the contact area of the corrugated sheath with the cushioning layer.
(2) Currently, corrugated sheaths and cushioning layers still lack the corresponding standard constraints in terms of dimensional fit. Under the condition of comprehensively considering the performance requirements of the cable in various aspects such as mechanical strength, axial water blocking and the like, different power cable suppliers adopt different technical schemes on the problem of whether the diameter of a wave trough at the inner side of the corrugated sheath is larger than the diameter of the outer side of the cable containing the buffer layer. Thus, under the action of gravity, the inside of the corrugated sheath above the cable of some suppliers does not come into effective contact with the buffer layer, as shown in fig. 1; the inside of the corrugated sheath over a portion of the supplier's cable is in operative contact with the buffer layer as shown in fig. 2. Clearly, a calculation method that can take both cases into account is needed.
(3) Early cables lack information such as factory test reports, so that basic data of the cables are not complete, and sufficient information is difficult to provide for calculating the contact area. Therefore, the calculation method of the contact area between the corrugated sheath and the buffer layer needs to have the capability of accessing measured data so as to deal with the situation that the cable information is insufficient.
How to calculate the surface area of the inner side of the corrugated sheath of the high-voltage power cable and quickly screen the cable section with the ablation hidden danger of the buffer layer of the high-voltage power cable is a problem which needs to be solved urgently at present.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a method for quickly screening ablation hidden danger cable sections based on the inner surface area of a corrugated sheath, which is reasonable in design, quick and accurate.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
a method for quickly screening ablation hidden danger cable sections based on the inner surface area of a corrugated sheath comprises the following steps:
step 1, approximately calculating the inner side surface area of a corrugated sheath of a high-voltage power cable according to the inner side surface area of the corrugated sheath in a single corrugated pitch;
and 2, calculating a screening threshold of the cable section with the ablation hidden danger of the buffer layer by using the contact ratio of the fault cable section recorded in the historical data according to the surface area of the inner side of the corrugated sheath of the high-voltage power cable, and quickly screening the cable section with the ablation hidden danger of the buffer layer through the screening threshold of the cable section with the ablation hidden danger of the buffer layer.
Moreover, the specific implementation method of the step 1 is as follows:
step 1.1, according to a cable factory test report or an actual measurement result, arranging to obtain the following data: length d of cable segment cable Nominal value, inside radius d of corrugated sheath OA Nominal value, wrinkle pitch d len Nominal value, wrinkle depth d dep Nominal value, corrugated sheath thickness d al A nominal value;
step 1.2, calculating the inner side surface area S of the wrinkle sheath according to the following formula total-pit ：
Moreover, the method for calculating the screening threshold of the cable section with the ablation hidden danger of the buffer layer in the step 2 comprises the following steps:
the method includes the steps of collecting fault cable segments { l ] under a specified voltage level i } i＝1,...,n The method includes the following steps that (1) data information of the outgoing cable is arranged, data required by the calculation method of the contact area and the inner surface area of the corrugated sheath are arranged, and if the data are insufficient, the steps are performed; otherwise entering the step three;
for all fault cable sections with insufficient data, actually testing the cable sections cut out during fault processing, supplementing the data required by the contact area calculation method, and entering the step three;
three, for all i =1, 8230, n, query l i If a contact ratio saving result exists, the step proceeds to step four; otherwise entering step fifthly;
fourthly, for fault cable sections with number i, required by contact area calculation methodComparing the data with historical data, and comparing the data required by the calculation method of the surface area of the inner side of the corrugated sheath with the historical data; if the two items of required data are not different from the historical data and the contact ratio storage result exists, the contact ratio storage result w (l) is used i ) Entering the step VI; otherwise, entering step fife, wherein:
fifthly, storing data required by the contact area calculation method into historical data for the fault cable section with the number i, calculating the total contact area according to the historical data, and obtaining S total (l i ) (ii) a The data required by the calculation method of the inner surface area of the wrinkle sheath is saved as historical data, so that the inner surface area of the wrinkle sheath is calculated to obtain S total-pit (l i ) (ii) a Calculating the contact ratio w (l) of the fault cable section i ) And saving the calculation result of the contact ratio;
sixthly, performing summarizing calculation to obtain a fault cable section contact ratio set { w (l) i )} i＝1,...,n And calculating to obtain a screening threshold t of the cable section with the potential ablation hazard of the buffer layer under the voltage level:
moreover, the concrete implementation method for rapidly screening the cable section with the ablation hidden danger of the buffer layer comprises the following steps:
making i } i＝1,...,n Cable segment set { q ] to be screened at same voltage level j } j＝1,...,m Arranging factory cable data information, collecting data required by the contact area and the calculation method of the surface area of the inner side of the corrugated sheath, and performing the second step if the data are insufficient; otherwise entering the step three;
for cable sections to be screened with insufficient data, actually testing the same-model same-batch cable sections, supplementing the data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath, and entering the step three;
three for all j =1, \ 8230;, m, query q j Whether a contact ratio calculation result is recorded before; for each specific j =1, \8230;, m, if there is a contact ratio save result, proceed to step four; otherwise entering step fifthly;
fourthly, comparing data required by the contact area calculation method with historical data of the cable segment to be screened with the serial number j, and comparing data required by the wrinkle sheath inner side surface area calculation method with historical data; if there is no difference between the two items of required data and the history data and there is a result of saving the touch ratio, the result w (q) of saving the touch ratio is used j ) Entering the step VI; otherwise, entering step fife;
fifthly, storing the data required by the contact area calculation method into historical data for the cable section to be screened with the serial number j, calculating the total contact area to obtain S total (q j ) (ii) a The data required by the calculation method of the inner surface area of the wrinkled jacket is stored as historical data, and the inner surface area of the wrinkled jacket is calculated according to the historical data to obtain S total-pit (q j ) (ii) a A contact ratio calculation w (q) is then calculated for the cable segment to be screened j ) Entering the step VI, wherein:
sixthly, calculating and obtaining a cable segment contact ratio set { w (q) to be screened j )} j＝1,...,m For all j =1, \ 8230;, m, the following determinations were made: if w (q) j ) When t is less than or equal to t, q is added j Adding the potential hazards into a hidden danger list, otherwise, adding q into the hidden danger list j Excluded from the hidden danger list. Entering step-quietness;
and finishing the output hidden danger list, and screening cable sections with the ablation hidden dangers of the cable buffer layer.
The invention has the advantages and positive effects that:
the method is reasonable in design, the screening threshold value of the ablation hidden danger cable section of the buffer layer is calculated according to the contact ratio of the fault cable section recorded in historical data by approximately calculating the surface area of the inner side of the corrugated sheath of the high-voltage power cable, the ablation hidden danger cable section function of the buffer layer is further realized, the method can be used for performing performance evaluation on the size matching condition of the corrugated sheath and the buffer layer of the high-voltage power cable, the buffer layer ablation hidden danger cable section list of the cable stock is given, and reference is provided for operation and maintenance of the high-voltage power cable.
Drawings
FIG. 1 is a schematic view of a condition of no contact between the corrugated sheath and the buffer layer over the cable;
FIG. 2 is a schematic view of the presence of contact between the corrugated jacket and the buffer layer over the cable;
FIG. 3 is an axial cross-sectional view of the interface of the corrugated sheath and cushioning layer;
FIG. 4 shows the approximate contact area between the corrugated sheath and the buffer layer at θ = θ P A plan sectional view.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
A method for quickly screening ablation hidden danger cable sections based on the inner surface area of a corrugated sheath comprises the following steps:
step 1, approximately calculating the surface area of the inner side of a corrugated sheath of the high-voltage power cable.
The method for approximately calculating the surface area of the inner side of the corrugated sheath of the high-voltage power cable is based on the following principle:
1. calculated decomposition of the inside surface area of a corrugated sheath
Due to the peak-valley position of the corrugated sheath, the following basic assumptions in accordance with engineering practice need to be made for calculating the corrugated sheath surface area:
assume that the contact area within each corrugation pitch is approximately the same;
the effect of the inclination angle of the embossing on the contact area is assumed to be negligible.
At this time, the contact area of the cushioning layer and the corrugated sheath can be decomposed into the sum of the contact areas of the cushioning layer and the corrugated sheath in each corrugated pitch. Since a corrugation pitch is small compared to the total length of the cable segment, the contact area at the ends of the cable less than one corrugation pitch can be approximated in corresponding proportions. The corrugated sheath surface area can similarly be decomposed, thereby obtaining:
in the formula, S total-pit Is the corrugated sheath surface area; s pit A corrugated sheath surface area within a single corrugated pitch; d cable Is the nominal value of the length of the cable segment; d len Is the nominal value of the corrugation pitch. So to obtain the overall corrugated jacket inside surface area of the cable, the corrugated jacket surface area within a single corrugation pitch needs to be calculated.
2. Approximate calculation of inside surface area of corrugated sheath within single corrugation pitch
Considering that the contact surface of the actual buffer layer and the corrugated sheath is a space curved surface, and taking the circle center position O of the corrugated sheath as an origin point in a radial plane of the cable, a rho-theta plane polar coordinate can be established as shown in figure 1. O 'is the centre of a circle of the cable core, and the critical points of the contact of the buffer layer and the corrugated sheath are marked as A and A'. As shown in fig. 3, on the basis of the ρ - θ plane coordinate, a three-dimensional coordinate system can be established with the axial direction of the cable as the Z direction, and the dashed line in the figure is a schematic representation of the contact surface between the buffer layer and the corrugated sheath. Obviously, within one corrugation pitch, if the contact surface function is z = f (ρ, θ), the corresponding contact area can be calculated by the following equation:
wherein Ω ρ θ is a projection of the curved inner surface of the corrugated sheath on the z =0 plane.
As described in the background section, the analytical expression of f (ρ, θ) is difficult to obtain. An approximation of the inside surface area of the corrugated sheath is obtained by surface integral calculation of a continuous micro-approximable function of the z = f (ρ, θ) surface. The patent proposes a method for approximate calculation of the inside surface area of a corrugated sheath in a single corrugation pitch. Straight line in theta =0 direction due to projection of curved surface inside corrugated sheath on z =0 planeLine symmetry, and the corrugated sheath inside curve within a single corrugation pitch is symmetric with the z =0 plane, so S is calculated pit The value of (a) is only required to finish the calculation of the integral of the curved surface multiplied by 4 times in the interval of pi being more than or equal to theta being more than or equal to 0 and Z being more than or equal to 0.
In terms of the integrand, as shown in FIG. 4, an approximate surface can be obtained
The functional expression within the interval is:
wherein d is dep Is the nominal value of the wrinkle depth; d OA Is the nominal value of the inside radius of the corrugated sheath.
The approximate expression for the inside surface area of the corrugated sheath within a single corrugation pitch is available as:
based on the principle, the approximate calculation method for the inner side surface area of the corrugated sheath of the high-voltage power cable comprises the following steps:
step 1.1, according to a cable factory test report or an actual measurement result, arranging to obtain the following data: length d of cable segment cable Nominal value, inside radius d of corrugated sheath OA Nominal value, wrinkle pitch d len Nominal value, wrinkle depth d dep Nominal value, corrugated sheath thickness d al A nominal value.
Step 1.2, calculating the inner side surface area S of the corrugated sheath according to the following formula total-pit . And (4) calculating the surface area of the corrugated sheath.
And 2, rapidly screening the cable section with the ablation hidden danger of the buffer layer of the high-voltage power cable according to the surface area of the inner side of the corrugated sheath of the high-voltage power cable.
The contact area of the corrugated sheath and the buffer layer on the whole cable depends on the size information of the length of the actual cable segment, the thickness of insulation and the like, and the size design of the high-voltage cable of each cable supplier is not consistent. Since the contact area mainly reflects the contact condition of the buffered layer between the cable insulation shield and the corrugated sheath, in order to realize the comparison of cables with different sizes, the invention provides a method for performing comparison by using the contact ratio.
On the basis that the contact area can be calculated or estimated, the contact ratio is calculated using the following equation:
wherein w is a contact ratio between the insulation shield and the corrugated sheath; s total-pit Is the inside surface area of the corrugated sheath.
The hidden danger cable section screening threshold value can be obtained according to the contact ratio information of the fault cable section, and the hidden danger cable section screening threshold value is compared with the contact ratio information of the cable to be screened to obtain a conclusion whether the cable to be screened contains the ablation hidden danger of the buffer layer.
According to actual needs, the rapid screening method for the cable section with the ablation hidden danger of the buffer layer can be operated for multiple times, and the contact ratio calculation result can be repeatedly reused on the premise that input data is not changed; if the contact area is calculated by other applications, the calculation result can be stored so as to facilitate the use of the method for rapidly screening the cable segment with the ablation hidden danger of the buffer layer, thereby improving the screening speed.
Based on the above description, the specific implementation method of this step includes the following steps:
step 2.1, calculating a screening threshold value of the cable section with the ablation hidden danger of the buffer layer, wherein the specific method comprises the following steps:
the method includes the steps of collecting fault cable segments { l ] under a specified voltage level i } i＝1,...,n Calculating the data information of all cables, i =1, \8230;, n, sorting factory reports, etc., and sorting the contact area and the surface area of the inner side of the corrugated sheathThe method comprises the following steps of obtaining data required by the method, and if the data are insufficient, performing the step II; otherwise, entering the step three.
And secondly, for all fault cable sections with insufficient data, actually testing the cable sections cut out during fault processing, supplementing the data required by the contact area calculation method, and entering the step three.
Three, for all i =1, 8230, n, query l i Whether there is a previous record of the contact ratio calculation result. For each specific i =1, \8230, n, if there is a contact ratio save result, proceed to step four; otherwise, entering step fife.
And fourthly, comparing data required by the contact area calculation method with historical data for the fault cable section with the number i, and comparing data required by the wrinkle sheath inner side surface area calculation method with historical data. If there is no difference between the two items of required data and the history data and there is a result of saving the contact ratio, the result w (l) of saving the contact ratio is used i ) Entering the step of sixteenth; otherwise, entering step fife.
Fifthly, storing data required by the contact area calculation method into historical data for the fault cable section with the number i, calculating the total contact area according to the historical data, and obtaining S total (l i ). The data required by the calculation method of the inner surface area of the wrinkle sheath is saved as historical data, so that the inner surface area of the wrinkle sheath is calculated to obtain S total-pit (l i ). Then, the contact ratio was calculated according to the following formula to obtain w (l) i ) And saves the result of the contact ratio calculation. Entering the step sixteenth.
Sixthly, calculating and obtaining a fault cable segment contact ratio set { w (l) i )} i＝1,...,n And calculating to obtain the screening threshold t of the cable section with the ablation hidden danger of the buffer layer under the voltage level according to the following formula.
Step 2.2, screening the cable section with the ablation hidden danger of the buffer layer
First pair and { l i } i＝1,...,n Cable segment set { q ] to be screened at same voltage level j } j＝1,...,m For all the cable data information of j =1, \ 8230;, m, sorting delivery reports and the like, collecting data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath, and entering a second step if the data are insufficient; otherwise, entering the step three.
And secondly, for the cable sections to be screened with insufficient data, actually testing the same-model same-batch cable sections, supplementing the data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath, and entering the step three.
Three, for all j =1, 8230, m, query q j Whether there is a previous record of the contact ratio calculation result. For each specific j =1, \8230, m, if there is a contact ratio save result, proceed to step four; otherwise, entering step fife.
Fourthly, comparing the data required by the contact area calculation method with historical data of the cable segment to be screened with the serial number j, and comparing the data required by the wrinkle sheath inner side surface area calculation method with the historical data. If the two items of required data are not different from the historical data and the contact ratio storage result exists, the contact ratio storage result w (q) is used j ) Entering the step VI; otherwise, entering step fife.
Fifthly, storing the data required by the contact area calculation method into historical data for the cable section to be screened with the serial number j, calculating the total contact area to obtain S total (q j ). The data required by the calculation method of the inner surface area of the wrinkled jacket is stored as historical data, and the inner surface area of the wrinkled jacket is calculated according to the historical data to obtain S total-pit (q j ). Then, the contact ratio calculation was performed according to the following formula to obtain w (q) j )。
Entering the step sixteenth.
Sixthly, calculating and obtaining a cable segment contact ratio set { w (q) to be screened j )} j＝1,...,m For all j =1, \ 8230;, m, the following determinations were made: if w (q) j ) When t is less than or equal to t, q is added j Adding the potential hazards into a hidden danger list, otherwise, adding q into the hidden danger list j Excluded from the hidden danger list. Step-wise is entered.
The output hidden danger list is trimmed. And finishing screening the cable section with the ablation hidden danger of the cable buffer layer.
The effect of the invention is verified by two examples below:
example 1
In the example, a cable section with ablation corrosion hidden danger of a buffer layer of a 220kV high-voltage power cable is screened. 3 sections of fault cable sections are shared, namely a fault section A, a fault section B and a fault section C; 4 cable sections to be screened are respectively a first conveying section, a second conveying section, a third conveying section and a third conveying section. All cables have no historical data and previous calculations are saved.
Firstly, screening threshold value calculation is carried out on cable sections with ablation hidden troubles of the buffer layer.
Step 1, collecting fault cable sections { l) under 220kV level i } i＝1,...,3 For all the cable data information of i =1, \8230;, 3, sorting delivery reports and the like, sorting the data required by the calculation method of the contact area and the inner side surface area of the corrugated sheath, and if the data is insufficient, entering the step 2; otherwise, entering the step 3.
And 2, for all fault cable sections with insufficient data, actually testing the cable sections intercepted during fault processing, supplementing the data required by the calculation method, and entering the step 3.
Through the first two steps, the input data of the sorted fault cable sets are as follows:
step 3, for all i =1, \8230, step 3, query l i Whether there is a previous record of the contact ratio calculation result. For each specific i =1, \ 8230;, 3, if there is a contact ratio holdIf the result is stored, the step 4 is entered; otherwise, entering the step 5.
And 5, for the fault cable section with the number i, storing data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath as historical data, calculating the contact area, and entering the step 5.1.
Step 5.1, calculating the surface area S of the inner side of the corrugated sheath according to the following formula total-pit . And (5) after the calculation of the surface area of the inner side of the corrugated sheath is finished, entering the step 5.2.
Step 5.2, then calculating the contact ratio according to the following formula to obtain w (l) i ) And saves the result of the contact ratio calculation. And 6, entering the step 6.
The above calculation results are collated in the following table:
step 6, summarizing and calculating to obtain a fault cable section contact ratio set { w (l) i )} i＝1,…,3 And calculating to obtain a screening threshold t of the potential electrochemical corrosion hidden danger cable section of the buffer layer under the voltage level according to the following formula:
in this sample, t =10.79% was calculated.
And then carrying out a screening process of the cable section with the ablation hidden danger of the buffer layer.
Step 1, for a 220kV voltage level cable segment set to be screened { q j } j＝1,...,4 For all j =1, \8230;, 4, cable data such as factory reports are sortedCollecting data required by a calculation method of the contact area and the surface area of the inner side of the wrinkle sheath, and entering the step 2 if the data are insufficient; otherwise, entering the step 3.
And 2, for all cable sections to be screened with insufficient data, actually testing the same-model same-batch cable sections, filling up the data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath, and entering the step 3.
Through the first two steps, the input data of the cable set to be screened after the arrangement is as follows:
step 3, query q for all j =1, \ 8230;, 4 j Whether there is a previous record of the contact ratio calculation result. For each specific j =1, \8230;, 4, step 5 is entered as the result is saved due to the absence of contact ratios.
And 5, storing the data required by the calculation method of the contact area and the surface area of the inner side of the wrinkle sheath into historical data for the cable segment to be screened with the number j, calculating the contact area, and entering the step 5.1.
Step 5.1, calculating the surface area S of the inner side of the corrugated sheath according to the following formula total-pit . And (5) after the calculation of the surface area of the inner side of the corrugated sheath is finished, entering the step 5.2.
Step 5.2, then calculating the contact ratio according to the following formula to obtain w (q) j ) And saves the result of the contact ratio calculation. And 6, entering the step 6.
The above calculation results are collated in the following table:
step 6, summarizing and calculating to obtain a cable segment contact ratio set { w (q) to be screened j )} j＝1,...,4 For all j =1, \8230and4, the following judgments were made: if w (q) j ) Q is less than or equal to 10.79, then q is added j Adding the potential hazards into a hidden danger list, otherwise, adding q into the hidden danger list j Excluded from the hidden danger list. And entering the seventh step.
And 7, arranging and outputting the hidden danger list to obtain a hidden danger list: { in the first transportation stage, in the second transportation stage }.
Example 2
The scenario of example 2 is that, on the basis that the screening of the cable section with the potential ablation hazard of the buffer layer of the high-voltage power cable is completed in the example 1, the buffer layer at the transport section is ablated to cause a fault, and after the actual measurement and data updating are performed on the fault section at the transport section, the screening of the cable section with the potential ablation hazard of the buffer layer needs to be performed again.
And calculating screening threshold values of the cable sections with the ablation hidden danger of the buffer layer.
Step 1, collecting fault cable sections { l) under 220kV voltage level i } i＝1,...,4 For all the cable data information of i =1, \8230;, 4, sorting delivery reports and the like, sorting the data required by the calculation method of the contact area and the inner side surface area of the wrinkle sheath, and if the data is insufficient, entering the step 2; otherwise, entering the step 3.
And step 2, for all fault cable sections with insufficient data, actually testing the cable sections cut out during fault processing, supplementing the contact area and the data required by the calculation method of the surface area inside the corrugated sheath, and entering step 3.
Through the first two steps, the input data of the sorted fault cable sets are as follows:
step 3, query l for all i =1, \ 8230;, 4 i Whether there is a previous record of the contact ratio calculation result. For each specific i =1, \ 8230;, 4, the result is saved due to the presence of the contact ratio, and step 4 is entered.
And 4, comparing data required by the contact area calculation method with historical data for the fault cable section with the serial number i, and comparing data required by the wrinkle sheath inner side surface area calculation method with historical data. If there is no difference between the two items of required data and the history data and there is a result of saving the contact ratio, the result w (l) of saving the contact ratio is used i ) Entering the step 6; otherwise, the step 5 is entered.
And 5, for the fault cable section with the number i, storing data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath as historical data, calculating the contact area, and entering the step 5.1.
Step 5.1, calculating the surface area S of the inner side of the corrugated sheath according to the following formula total-pit . And (5) after the calculation of the inner surface area of the corrugated sheath is finished, entering the step 5.2.
Step 5.2, then the contact ratio calculation is performed according to the following formula to obtain w (l) i ) And saves the result of the contact ratio calculation. And 6, entering the step 6.
It is clear that, for i =1, \8230;, 3, the contact ratio has a storage result, and the data required for the calculation method of the contact area and the surface area inside the wrinkled sheath are not different from the historical data, and w (l) can be directly obtained i ). For i =4, since the data required for the contact area and the wrinkle sheath inside surface area calculation method is different from the historical data, it is necessary to proceed to the 5 th step for calculation. The results are summarized below.
The above calculation results are collated in the following table:
step 6, summarizing and calculating to obtain a fault cable section contact ratio set { w (l) i )} i＝1,...,4 And calculating the screening threshold t of the potential electrochemical corrosion hazard cable section of the buffer layer under the voltage level according to the following formula:
in this sample, it was calculated that t =12.04%.
And then, carrying out a screening process of the cable section with the ablation hidden danger of the buffer layer.
Step 1, for a 220kV voltage level cable segment set to be screened { q j } j＝1,...,3 For all the cable data information of j =1, \8230;, 3, sorting delivery reports and the like, collecting data required by the calculation method of the contact area and the inner side surface area of the wrinkle sheath, and entering the step 2 if the data are insufficient; otherwise, entering the step 3.
And 2, for all cable sections to be screened with insufficient data, actually testing the same-model same-batch cable sections, filling up the data required by the calculation method of the contact area and the surface area of the inner side of the corrugated sheath, and entering the step 3.
Through the first two steps, the input data of the cable set to be screened after the arrangement is as follows:
step 3, for all j =1, \8230, step 3, query q j Whether there is a previous record of the contact ratio calculation result. For each specific j =1, \8230;, 3, the result is saved due to the presence of the contact ratio, and step 4 is entered.
Step 4, calculating the contact area of the cable segment to be screened with the serial number jAnd comparing the required data with historical data, and comparing the required data with the historical data by using the calculation method for the surface area of the inner side of the corrugated sheath. If the two items of required data are not different from the historical data and the contact ratio storage result exists, the contact ratio storage result w (q) is used j ) Entering the step 6; otherwise, the step 5 is entered.
It is clear that w (q) can be directly obtained for j =1, \8230;, 3, the contact ratio has a stored result and the data required for the contact area calculation method is not different from the history data j )。
Step 6, summarizing and calculating to obtain a cable segment contact ratio set { w (q) to be screened j )} j＝1,...,3 For all j =1, \8230;, 3, the following judgments were made: if w (q) j ) Q is less than or equal to 12.04, then q is j Adding the potential danger list, otherwise, adding q to the potential danger list j Excluded from the hidden danger list. And 7, entering the step.
And 7, sorting and outputting the hidden danger list to obtain a hidden danger list: { in second segment }.
It should be emphasized that the embodiments described herein are illustrative and not restrictive, and thus the present invention includes, but is not limited to, the embodiments described in the detailed description, as well as other embodiments that can be derived by one skilled in the art from the teachings herein.
Claims (1)
1. A method for rapidly screening ablation hidden danger cable sections based on the inner surface area of a corrugated sheath is characterized by comprising the following steps: the method comprises the following steps:
step 1, approximately calculating the inner side surface area of a corrugated sheath of a high-voltage power cable according to the inner side surface area of the corrugated sheath in a single corrugated pitch;
step 2, calculating a screening threshold of the cable section with the ablation hidden danger of the buffer layer by using the contact ratio of the fault cable section recorded in historical data according to the surface area of the inner side of the corrugated sheath of the high-voltage power cable, and quickly screening the cable section with the ablation hidden danger of the buffer layer through the screening threshold of the cable section with the ablation hidden danger of the buffer layer;
the specific implementation method of the step 1 comprises the following steps:
step 1.1, according to a cable factory test report or an actual measurement result, arranging to obtain the following data: length d of cable segment cable Nominal value, inside radius d of corrugated sheath OA Nominal value, wrinkle pitch d len Nominal value, wrinkle depth d dep Nominal value, wrinkled jacket thickness d al A nominal value;
step 1.2, calculating the surface area S of the inner side of the wrinkled jacket according to the following formula total-pit ：
When the screening threshold value of the cable segment with the ablation hidden danger of the buffer layer is calculated in the step, the set of the fault cable segments under the specified voltage level is set as { l } i } i＝1,...,n For the fault cable section with the number i, the data required by the contact area calculation method is stored as historical data, the total contact area is calculated according to the historical data, and S is obtained total (l i ) (ii) a The data required by the calculation method of the inner surface area of the wrinkled jacket is stored as historical data, and the inner surface area of the wrinkled jacket is calculated according to the historical data to obtain S total-pit (l i ) (ii) a Then, the contact ratio was calculated according to the following formula to obtain w (l) i ) And saving the contact ratio calculation result:
the summary calculation results in a set of contact ratios of the fault cable sections { w (l) } i )} i＝1,...,n And calculating a screening threshold t of the cable section with the potential ablation hazard of the buffer layer under the voltage level according to the following formula:
when the screening threshold value of the cable segment with the ablation hidden danger of the buffer layer is calculated, the data required by the contact area calculation method for the cable segment to be screened with the number j is saved as historical data, the total contact area is calculated, and S is obtained total (q j ) (ii) a The data required by the calculation method of the inner surface area of the wrinkle sheath is saved as historical data, so that the inner surface area of the wrinkle sheath is calculated to obtain S total-pit (q j ) (ii) a Then, the contact ratio calculation was performed according to the following formula to obtain w (q) j )：
The contact ratio set { w (q) of the cable segments to be screened is obtained through summarizing and calculating j )} j＝1,...,m For all j =1, \ 8230;, m, the following determinations were made: if w (q) j ) When t is less than or equal to t, q is added j Adding the potential danger list, otherwise, adding q to the potential danger list j Excluded from the hidden danger list.
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Address after: No. 8, Haitai Huake 4th Road, Huayuan Industrial Zone, High tech Zone, Binhai New Area, Tianjin, 300384 Patentee after: ELECTRIC POWER SCIENCE & RESEARCH INSTITUTE OF STATE GRID TIANJIN ELECTRIC POWER Co. Patentee after: STATE GRID TIANJIN ELECTRIC POWER Co. Patentee after: STATE GRID CORPORATION OF CHINA Address before: No.8, Haitai Huake 4th Road, Xiqing District, Tianjin 300384 Patentee before: ELECTRIC POWER SCIENCE & RESEARCH INSTITUTE OF STATE GRID TIANJIN ELECTRIC POWER Co. Patentee before: STATE GRID TIANJIN ELECTRIC POWER Co. Patentee before: STATE GRID CORPORATION OF CHINA |