KR20170103353A - Optimum current carrying capability calculation method of underground power cables - Google Patents
Optimum current carrying capability calculation method of underground power cables Download PDFInfo
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- KR20170103353A KR20170103353A KR1020160026084A KR20160026084A KR20170103353A KR 20170103353 A KR20170103353 A KR 20170103353A KR 1020160026084 A KR1020160026084 A KR 1020160026084A KR 20160026084 A KR20160026084 A KR 20160026084A KR 20170103353 A KR20170103353 A KR 20170103353A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16528—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values using digital techniques or performing arithmetic operations
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/30—Measuring the maximum or the minimum value of current or voltage reached in a time interval
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/32—Compensating for temperature change
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Abstract
Description
The present invention relates to a method for calculating an optimum allowable current of an underground power cable, which can calculate an optimum allowable current for an underground power cable by eliminating under-evaluation of a conductor temperature and underestimation of an allowable current.
Generally, the permissible current of a power cable installed in the ground is calculated by the heat circuit equation of the power cable system, which indicates the process of heat generated from the power cable to the surrounding medium of the underground power cable.
On the other hand, the thermal circuit of the power cable system consists of a thermal circuit of the underground power cable itself consisting of a conductor, an insulator, a sheath and a method layer (or exterior), and a thermal circuit of the surrounding medium surrounding the power cable. The power cable consists of a complex heat circuit in which the heat generated by each power cable and the heat generated by the other power cable interact with each other as at least one of the power cables is built in the surrounding medium.
The thermal constants and calculation methods of the thermal circuit consisting of this power cable itself and the surrounding medium are well documented in IEC 60287, which is internationally accepted. The IEC 60287 standard calculates the allowable current in two ways depending on the type and size of the power cable. In other words, the IEC 60287 standard has an equal load method, which is used when the type and size of the power cable are the same, and an unequal load method, which is used when the type and size of the power cable are not the same. However, the unequal load method can be used even when the type and size of the power cable are the same.
Therefore, as shown in the flowchart of FIG. 1, when the type and size of the power cable are different, the conventional method of calculating the allowable current of the underground power cable uses the unequal load method. If the type and size of the power cable are the same, Or an unequal load scheme.
Here, the Equal load method calculates the current under the condition that the allowable temperature is not exceeded only for the power cable which is thermally weakest in the heat circuit of the power cable system, and determines this as the allowable current representative of the whole heat circuit of the power cable system There is only one allowable current. Unequal load method is a method to calculate the current that does not exceed each allowable temperature for all the power cables in the heat circuit of the power cable system and determine them as the allowable currents of the thermal circuit of the power cable system. Lt; / RTI >
In the equal load method, the conductor temperature of the thermally weakest power cable is the allowable temperature of the power cable, but the conductor temperature of the other power cable is underestimated, which is calculated to be lower than the allowable temperature of the power cable. In the unequal load method, the conductor temperature of the power cable installed in the heat circuit of the power cable system is equal to the allowable temperature, but the permissible current is limited by the number of the power cables due to the mutual thermal effect.
Therefore, when the allowable current is calculated using the equal load method or the unequal load method included in the IEC 60287 standard, underestimation of the conductor temperature and underestimation of the allowable current occur, which limits the calculation of the optimum allowable current for the underground power cable .
On the other hand, the transmission capacity to the underground line is made up of three phases (A phase, B phase, C phase) and the allowable current of each phase is calculated based on one permissible current which has almost no imbalance.
If several lines are installed in the heat circuit of the power cable system, the installation positions of the power cables corresponding to each phase are different from each other. When calculating by the unequal load method, the allowable currents of the respective phases are calculated differently, It can not reflect the reality of operating capacity.
In addition, since the conductor temperature is calculated differently according to the equal load method, it can not provide a method of operating the conductor temperature of the power cable at a constant value. In addition, it is more realistic that the type and size of the power cable installed in the heat circuit of the power cable system are different from each other.
Considering this real situation, considering the type and size of power cable such as power transmission class and power class cable, it is necessary to use the maximum conductor temperature without exceeding the allowable temperature standard of power cable and to set the optimum allowable current And to provide a method for providing such information.
The present invention was invented to overcome the above-mentioned problems, and it is an object of the present invention to solve the above-mentioned problems and to provide an underground power cable capable of calculating an optimal allowable current for underground power cables by eliminating under- And an object of the present invention is to provide a method of calculating an optimum allowable current.
The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood from the following description.
According to an aspect of the present invention, there is provided a method of calculating an optimum allowable current of an underground power cable, comprising: a first step of grouping a plurality of power cables installed in the ground by respective lines; A second step of setting an allowable current underestimation range according to installation positions of the power cables included in each of the grouped lines; A third step of setting a conductor temperature underestimation range according to installation positions of the power cables included in each of the grouped lines; A fourth step of assigning one of the allowable current values included in the set allowable current underestimation range to the allowable current values of the respective lines; A fifth step of calculating the conductor temperature for each line by substituting the allowable current value of each of the allocated lines into the column circuit equation of the power cable system; A sixth step of determining whether the calculated conductor temperatures for the respective lines converge to a predetermined allowable temperature range for each of the lines; When the calculated conductor temperatures for the respective lines converge to a predetermined allowable temperature range for each of the lines, the calculated allowable current values of the assigned lines are outputted as the optimum allowed current values of the respective lines, If it is determined that the allowable current value of each of the lines is increased or decreased, the fourth through sixth steps are repeated until convergence to a predetermined allowable temperature range for each line is made, And outputting an allowable current value of each line as an optimal allowable current value of each line.
And if it does not converge in the seventh step, the allowable current value of each of the allocated lines is increased or decreased in consideration of the set allowable current underexpanded range.
The following effects can be expected from the present invention.
First, the power transmission capacity can be increased by eliminating the excess power. That is, it is possible to solve the conductor temperature underestimation and allowable current underestimation, thereby increasing the transmission capacity of the power cable system.
Next, the allowable current calculation method independent of the type and size of the power cable can be suggested. That is, it is possible to overcome the limitations of the equal load method and the unequal load method which are divided according to the type and size of the power cable.
Finally, it is possible to suggest a management method for each track. That is, it is possible to increase the transmission capacity by suggesting a line-by-line management method in the allowable current calculation method according to the conventional position basis.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing a method of calculating an optimum allowable current of a conventional underground power cable. FIG.
2 is a flowchart showing a method of calculating an optimum allowable current of an underground power cable according to a preferred embodiment of the present invention.
The present invention relates to a method for calculating an optimum allowable current of an underground power cable for calculating an optimum allowable current for an underground power cable installed in the ground.
Particularly, the method of calculating the optimum permissible current of the underground power cable according to the present invention eliminates the underestimation of the conductor temperature and the under current underestimation of the permissible current generated in the equal load method and the unequal load method of the conventional IEC 60287 standard, It is possible to optimally operate the underground power cable by calculating the optimum allowable current.
This feature is achieved by grouping a plurality of power cables installed in the ground by each line, setting the allowable current underestimation range and the conductor temperature underestimation range for the power cable included in each line, One of the current values is set as the allowable current value of each line, and it is substituted into the heat circuit equation of the power cable system to calculate the conductor temperature for each line. Then, the conductor temperature of each line is converged It is possible to calculate the optimum allowable current of each line and to increase or decrease the allowable current value of each line until convergence if it is not converged.
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for calculating an optimum allowable current of an underground power cable according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIG. 2, a method for calculating the optimum allowable current of an underground power cable according to a preferred embodiment of the present invention includes a grouping step S100 for each line, an allowable current underestimation range setting step S200, (S600), and a step S700 of outputting an allowable current value (S700). The range setting step S200, the allowable current value assigning step S400, the conductor temperature calculating step S500, the conductor temperature convergence discriminating step S600, do.
First, the grouping step S100 according to the first step is a step of grouping a plurality of power cables installed in the ground to be managed into lines of three phases.
That is, a plurality of power cables are classified into respective lines so that the plurality of power cables can be managed for each of the lines and the optimum allowable current can be calculated for each line.
Next, in the second step, the allowable current underestimation range setting step S200 is a step of setting a permissible current underestimation range for a plurality of power cables included in each of the lines grouped in the first step.
That is, since the power cables have different installation positions and allowable current values for the power cables are different according to their installation positions, the maximum allowable current value with the largest allowable current value and the minimum allowable current value with the smallest allowable current value The allowable current underestimation range is set to the maximum value and the minimum value, respectively.
At this time, the reason for setting the allowable current underestimation range is to roughly provide a range of the allowable current value that can be allocated in the allowable current value allocating step (S400), which will be described later.
Next, in the third step, the conductor temperature underestimation range setting step S300 is a step of setting conductor temperature underestimation ranges for a plurality of power cables included in each of the lines grouped in the first step.
That is, since the power cables are different in installation position and the conductor temperature for the power cables is different depending on the installation position, the maximum conductor temperature with the highest conductor temperature and the minimum conductor temperature with the lowest conductor temperature are set as the maximum temperature and the minimum And the conductor temperature underestimation range is set as the temperature.
The reason why the conductor temperature underestimation range is set here is to roughly provide a range of the conductor temperature calculated in the conductor temperature calculation step S500 described later.
Next, in the fourth step of allocating the allowable current value (S400), one of the allowable current values included in the allowable current undershoot range for each line set in the second step is assigned to each allowable current value for each line .
That is, the allowable current value included in the allowable current underestimation range for each line is assigned as the allowable current value for each line.
At this time, the allowable current values allocated to the respective lines are candidate values that can be the optimum allowable current values according to the conductor temperature calculating step S500 and the conductor temperature convergence determining step S600, which will be described later.
Next, in the fifth step S500 of calculating the conductor temperature, the allowable current values for the respective lines allocated in the fourth step are substituted into the column circuit equation of the power cable system to calculate the conductor temperature for each line .
That is, the conductor temperature for each line is calculated through a temperature analysis process in which the candidate values assigned to the allowable current values of the respective lines are substituted into the column circuit equation of the power cable system.
The reason why the conductor temperature is calculated according to the allowable current value, which is a candidate value, is to determine whether the conductor temperature calculated in the conductor temperature convergence determination step S600, which will be described later, converges to the allowable temperature range.
Next, in the sixth step S600, the conductor temperature convergence determination step S600 determines whether the conductor temperatures for the respective lines calculated in the fifth step converge to the allowable temperature ranges for the respective lines.
Next, in the seventh step of outputting the optimum allowable current value (S700), the allowable current value for each line is calculated as the optimum allowable current value for each line according to the convergence in the sixth step And increases or decreases the allowable current value for each line until output or convergence, and estimates the allowable current value as the optimum allowable current value.
That is, when the conductor temperature for each line converges to the predetermined allowable temperature range for each line, the allowable current value of the assigned line is outputted as the optimum allowable current value of each line and is terminated.
On the other hand, if the conductor temperature for each line does not converge to the preset allowable temperature range for each line, the allowable current value of each line assigned to each line is taken into account within the allowable current under- And then repeats the fourth through sixth steps until it converges to a predetermined allowable temperature range for each of the lines. Then, the allowable current values of the respective lines, which are increased or decreased finally, And outputs the allowable current value to terminate.
Therefore, when the first through seventh steps are performed, the optimum current values for the respective lines are obtained as described above. By setting the allowable currents for the respective lines, the transmission capacity is increased and the underground power cable is operated optimally can do.
The above-described embodiments are merely illustrative, and various modifications may be made by those skilled in the art without departing from the scope of the present invention.
Therefore, the true technical protection scope of the present invention should include not only the above embodiments but also various other modified embodiments according to the technical idea of the invention described in the following claims.
S100: Grouping step by line
S200: Step of setting the allowable current underestimation range
S300: Conductor temperature underestimation range setting step
S400: Acceptance current value assignment step
S500: Conductor temperature calculation step
S600: Step of judging whether the conductor temperature converges
S700: Outputting the Optimum Permissible Current Value
Claims (2)
A second step of setting an allowable current underestimation range according to installation positions of the power cables included in each of the grouped lines;
A third step of setting a conductor temperature underestimation range according to installation positions of the power cables included in each of the grouped lines;
A fourth step of assigning one of the allowable current values included in the set allowable current underestimation range to the allowable current values of the respective lines;
A fifth step of calculating the conductor temperature for each line by substituting the allowable current value of each of the allocated lines into the column circuit equation of the power cable system;
A sixth step of determining whether the calculated conductor temperatures for the respective lines converge to a predetermined allowable temperature range for each of the lines;
When the calculated conductor temperatures for the respective lines converge to a predetermined allowable temperature range for each of the lines, the calculated allowable current values of the assigned lines are outputted as the optimum allowed current values of the respective lines, If it is determined that the allowable current value of each of the lines is increased or decreased, the fourth through sixth steps are repeated until convergence to a predetermined allowable temperature range for each line is made, And outputting an allowable current value of each line as an optimal allowable current value of each line, and terminating the process.
In the seventh step
And if it does not converge, the allowable current value of each of the allocated lines is increased or decreased in consideration of the set permissible current underexpanding range.
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020160026084A KR20170103353A (en) | 2016-03-04 | 2016-03-04 | Optimum current carrying capability calculation method of underground power cables |
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| KR1020160026084A KR20170103353A (en) | 2016-03-04 | 2016-03-04 | Optimum current carrying capability calculation method of underground power cables |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111177956A (en) * | 2019-12-05 | 2020-05-19 | 国网浙江省电力有限公司电力科学研究院 | Finite element calculation method for current-carrying capacity of direct-buried cable considering soil heat-moisture coupling |
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2016
- 2016-03-04 KR KR1020160026084A patent/KR20170103353A/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111177956A (en) * | 2019-12-05 | 2020-05-19 | 国网浙江省电力有限公司电力科学研究院 | Finite element calculation method for current-carrying capacity of direct-buried cable considering soil heat-moisture coupling |
| CN111177956B (en) * | 2019-12-05 | 2023-08-15 | 国网浙江省电力有限公司电力科学研究院 | Direct buried cable current-carrying capacity finite element calculation method considering soil thermal-wet coupling |
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