JP5533742B2 - Power wiring selection method and selection device - Google Patents

Description

The present invention relates to a selection method and a selection device for a power wiring newly installed in parallel with an existing power wiring.

When a new power wiring is installed in parallel with the existing power wiring, the specifications of the new power wiring must be determined so that the voltage fluctuation amount during power transmission is within the allowable value range and the power wiring temperature is equal to or lower than the allowable value. Usually, the specifications of power wiring are determined by the following procedure. That is, the size of the power wiring is selected based on the allowable current table so that the rated current calculated for each load is not more than the allowable current value of the power wiring. Then, calculate the amount of voltage fluctuation at start-up and operation of the load, and if the calculated voltage fluctuation amount exceeds the allowable value, the power wiring is increased in size and the above calculation is performed again. Select power wiring that is within the allowable range.

However, the above method has a problem that it requires a lot of time because it depends on human hands. Therefore, in Patent Document 1, the calculation formula subroutine and the OS are stored in a floppy disk ("floppy" is a registered trademark) and input from an input device, and program conditions and parameters are input interactively. An invention of a power cable selection method is disclosed in which current calculation of a cable (power wiring), cable selection table creation, and conductor temperature calculation results are automatically output via an output device.

JP-A-1-178875

However, in the invention of the power cable selection method described in Patent Document 1, it is not assumed that a power wiring is newly installed in parallel with the existing power wiring, and thus there are the following restrictions.
(A) Calculation is possible only under the condition that all power wirings have the same characteristics (same diameter and same material). For this reason, when a power wiring is newly installed in parallel with the existing power wiring, the new power wiring must be the same type as the existing power wiring.
(B) In the temperature calculation of the power wiring, the influence of the temperature rise due to the peripheral power wiring can only be considered in a simplified manner.
(C) Only a case where a single motor is connected can be handled, and a case where a plurality of motors are connected or a temporary voltage fluctuation at the time of starting the motor cannot be handled.

The present invention has been made in view of such circumstances, and it is possible to select a new power wiring having a characteristic different from that of the existing power wiring, and to calculate the temperature of the new power wiring including the influence of the power wiring arranged around. Furthermore, it aims at providing the selection method and selection apparatus of the power wiring which can respond also to several load.

The present invention relates to a power wiring selection method, a selection device, and a program, wherein the current value of the existing power wiring and the new power wiring in an electric circuit in which the new power wiring is connected in parallel to the existing power wiring Calculated from the specifications of the wiring and the new power wiring, the power supply voltage, and the active and reactive power of the load. Based on the calculated current values, the amount of voltage fluctuation between the both ends of the existing and new power wiring, the existing power wiring and the new power By calculating each temperature of the power wiring, it is possible to select a new power wiring having characteristics different from those of the existing power wiring.
The “new installation” in the present invention includes a case where the power wiring is updated (replaced) in addition to the case where the power wiring is added.

The procedure for selecting a new power wiring using the power wiring selection method (selection device) is shown below.
(A1) In the first input step, the specifications of the existing power wiring and the new power wiring, the power supply voltage, and the active power and reactive power of the load are input via the input means. Here, the specifications of the power wiring are the resistance value, reactance value, number of strips, and the like of the power wiring.
(A2) The current value of the existing power wiring and the new power wiring in the electric circuit in which the existing power wiring and the new power wiring are connected in parallel by the current calculation step (current calculation means) It is calculated from the specifications of the new power wiring, the power supply voltage, and the active power and reactive power of the load.
(A3) The voltage fluctuation calculation step (voltage fluctuation calculation means) calculates the voltage fluctuation amount at both ends of the existing power wiring and the existing power wiring from the specifications of the existing power wiring and the new power wiring and the calculated current values. Then, it is determined whether the voltage fluctuation amount is within the allowable value A range. When the voltage fluctuation amount exceeds the allowable value A, the first update step (first update means) performs update to increase the size or number of the new power wiring, and the above (A2) Return.

(A4) In the second input step, wiring laying conditions for the existing power wiring and the new power wiring are input via the input means. Here, the wiring laying conditions of the power wiring include the power wiring laying environment (air, pipe, trough, etc.), the burying position when burying in the ground, and the specifications of the peripheral power wiring.
(A5) The temperature calculation step (temperature calculation means) calculates the temperature of the existing power wiring and the new power wiring from the wiring laying conditions of the existing power wiring and the new power wiring and the calculated current values, It is determined whether or not each temperature is equal to or less than an allowable value B. When the temperature of the existing power wiring or the new power wiring exceeds the allowable value B, the size (cross-sectional area) or the number of strips of the new power wiring is increased by the first updating step (first updating means). The update to be performed is performed, and the process returns to (A2).

In the present invention, selecting an appropriate new power wiring by selecting a small size power wiring as the initial value of the new power wiring, and gradually increasing the size or number of the new power wiring. Can do.

In the present invention, when the temperatures of the existing power wiring and the new power wiring calculated in (A5) are equal to or lower than the allowable value B, the second updating step (second updating means) An update to reduce the size (cross-sectional area) or the number of strips of the new power wiring may be performed, and the process may return to (A2). In that case, when the temperature of the existing power wiring or the new power wiring exceeds the allowable value B, the latest new power in which the temperature of the existing power wiring and the new power wiring is equal to or lower than the allowable value B. Wiring is the optimum new power wiring.
In the said structure, the optimal new power wiring can be selected by considering size reduction of the new power wiring or reduction in the number of strips.

In the present invention, the current value of the existing power wiring and the new power wiring in the electric circuit in which the new power wiring is connected in parallel to the existing power wiring, the specifications of the existing power wiring and the new power wiring, the power supply voltage, and the effective power of the load and Calculated from the reactive power, and calculates the voltage fluctuations at both ends of the existing and new power wirings and the temperatures of the existing power wiring and the new power wiring based on the calculated current values. The power wiring can be selected. As a result, power wiring purchase costs and construction costs can be reduced, and new power wiring can be optimized even if existing power wiring is discontinued or the same wiring route cannot be selected. It is.

Further, according to the present invention, not only the temperature rise effect by the peripheral power wiring can be expected in the temperature calculation of the power wiring, but also the case where there are a plurality of loads can be handled.

It is a functional block diagram which shows the selection apparatus of the electric power wiring which concerns on one embodiment of this invention. It is the model which showed the hardware constitutions of the selection apparatus. It is a flowchart for demonstrating the selection method of the electric power wiring which concerns on one embodiment of this invention. It is a schematic diagram of the electric circuit with which the power supply and load were connected by one power wiring. It is a schematic diagram of the electric circuit with which the power supply and load were connected by two electric power wiring. It is a schematic diagram of an electric circuit in which a power source and a load are connected by n power wires.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

The power generated at the power plant passes through the substation and is consumed by loads such as factory equipment and households. The power plant and the load are connected by power wiring.

When a current is passed through the power wiring, the temperature of the power wiring rises, so an allowable temperature is set for each type of power wiring. Further, if a large amount of power is applied to a thin power wiring, the amount of voltage fluctuation increases and the terminal voltage may deviate from the rated value. Therefore, when installing a new power line in parallel with the existing power line, the specifications of the new power line must be determined so that the voltage fluctuation during transmission is within the allowable range and the power line temperature is below the allowable level. Don't be.

When dissimilar power wirings are connected in parallel, there may occur a phenomenon in which the load is unbalanced between the power wirings, that is, a phenomenon in which one power wiring exceeds its capacity and the other power wiring leaves a surplus. The present invention makes it possible to select a new power wiring having characteristics different from those of the existing power wiring. In selecting the new power wiring, the power load of each power wiring is derived from the specifications of the existing power wiring and the new power wiring, and the power wiring temperature and voltage fluctuation amount are evaluated for the derived power load. Select the optimal new power wiring.

[Current calculation method]
First, a method for calculating the current values of the existing power wiring and the new power wiring in the electric circuit connected in parallel will be described.
When the power source and the load are connected by a single power wiring, the power wiring can be expressed by a series connection of an electric resistance R (Ω) and a reactance L (H) except for the long-distance power wiring (see FIG. 4). In the following description, the reactance L is described as X (= 2πfL). Where f is the frequency of the current.
When the active power P (W) and the reactive power Q (var) are transmitted to the power wiring, the relational expressions (1) to (3) are established.

Assuming that the unit of the active power P is MW, the unit of the reactive power Q is Mvar, and the reference capacity TB of the power transmission system is 10 (MVA), the equations (1) and (2) are expressed by the equations (4) and (5). It becomes like this.

As shown in FIG. 5, in the electric circuit in which the existing power wiring and the new power wiring are connected in parallel, the resistance of the existing power wiring and the new power wiring is R ₁ , R ₂ , the reactance is X ₁ , X ₂ , and the active power is Assuming that P ₁ , P ₂ , reactive power is Q ₁ , Q ₂ , and current values are I ₁ , I ₂ , the following equations (6) to (9) are expanded by expanding the equations (3) to (5). Is established.

Further, the total sum ΣP of active power and the total sum ΣQ of reactive power flowing through the existing power wiring and the new power wiring are expressed by equations (10) and (11).

In practice, Vs, ΣP, ΣQ, R ₁ , X ₁ , R ₂ , X ₂ are known quantities, and Vr, P ₁ , Q ₁ , I ₁ , P ₂ , Q ₂ , I ₂ are unknown quantities. Hereinafter, a method of calculating an unknown amount from a known amount will be described using equations (6) to (11).

Substituting (10) and (11) into (6) and rearranging results in (12) and (13).

The expression (14) is obtained by comparing the expressions (6) and (13), and the expression (15) is obtained by comparing the expressions (6) and (12).

Subsequently, for formula (7), substituting formulas (10) and (11) and rearranging results in formulas (16) and (17). Compare formulas (7) and (17). By doing so, the equation (18) is obtained, and the equation (18) is obtained by comparing the equations (7) and (16).

Next, when rearranged as (14) Formula × (R ₁ + R ₂ ) + (18) Formula × (X ₁ + X ₂ ), Formula (20) is obtained.

Similarly, when arranged as (14) Formula × (X ₁ + X ₂ ) − (18) Formula × (R ₁ + R ₂ ), Formula (21) becomes (15) Formula × (R ₁ + R ₂ ) + (19) When arranged as Formula x (X ₁ + X ₂ ), Formula (22) is obtained, and when Formulated as Formula (15) × (X ₁ + X ₂ ) − (19) Formula x (R ₁ + R ₂ ), Formula (23) is obtained. It is done.

The unknown quantities P ₁ , Q ₁ , P ₂ , Q ₂ can be calculated from the known quantities ΣP, ΣQ, R ₁ , X ₁ , R ₂ , X ₂ using the above equations (20) to (23). . The unknown amounts I ₁ and I ₂ can be calculated from the equations (8) and (9) after obtaining Vr using the equation (24) obtained by modifying the equation (6).

Next, a case where the power source and the load are connected by three or more power wires will be described.
As shown in FIG. 6, when there are n power wirings, the power source and the load are replaced by one power wiring by replacing all power wirings other than the power wiring to be obtained with one equivalent power wiring. It can be handled as a connected electrical circuit.

When the power wiring L ₂ to the power wiring L _n are combined into one equivalent power wiring, the resistance R ₁ ′ of the equivalent power wiring can be expressed by equation (25) and the reactance X ₁ ′ can be expressed by equation (26). it can. However, “Re” is an operator indicating the real part of the complex number in parentheses, and “Im” is an operator indicating the imaginary part of the complex number in parentheses.

(25) and (26) resistors _{R 1} and the reactance _{X 1} of the resistor _{R 1} 'and the reactance _{X 1'} and the power line _{L 1} of the calculated equivalent power wires from the equation (20) to (23) below the by substituting for, it is possible to obtain the active and reactive power of the power line L ₁ and equivalent power wiring, using the value, the current value from (24) and (8) and (9) Can be calculated.

The same applies in determining the active and reactive power of the power line L _2. That is, when the power wirings excluding the power wiring L ₂ are combined into one equivalent power wiring, the resistance R ₂ ′ of the equivalent power wiring is expressed by the equation (27) and the reactance X ₂ ′ is expressed by the equation (28). The equivalent resistance R ₂ ′ and reactance X ₂ ′ of the power wiring and the resistance R ₂ and reactance X ₂ of the power wiring L ₂ may be substituted into the equations (20) to (23). Hereinafter, the current value can be calculated for other power wirings in the same manner.

[Temperature calculation method]
A method of calculating the temperature of the existing power wiring and the new power wiring from the wiring laying conditions of the existing power wiring and the new power wiring and the calculated current value will be described.
The increase in current is directly connected to the temperature rise of the power wiring. The energizing current at the allowable temperature of the insulator used in the power wiring becomes the maximum energizing current of the power wiring.
First, the temperature calculation method of the power wiring A when the power wiring A and the power wiring B are laid in parallel in the ground will be described.

The temperature of the power wiring A can be expressed by the following equation from the thermal equation (see Japan Electric Wire Manufacturers Association Standard JCS No. 168).
Temperature of power wiring A = base temperature + rising temperature of power wiring A
+ Temperature rise due to power wiring B with respect to power wiring A (29)
Here, the base temperature is the ambient temperature when there is no power wiring.

Further, the rising temperature of the power wiring A can be obtained by the following equation.
Temperature rise of power wiring A = electric resistance of power wiring A × (current value of power wiring A) ²
× (Thermal resistance of power wiring A to the surface of power wiring + loss rate of power wiring A × soil thermal resistance of power wiring A)
+ Temperature rise due to dielectric loss of power wiring A (30)

On the other hand, the temperature rise by the power wiring B with respect to the power wiring A can be obtained by the following equation.
Temperature rise due to power wiring B with respect to power wiring A = {(1 + the sheath loss rate of power wiring B)
× loss rate of power wiring B × electric resistance of power wiring B × (current value of power wiring B) ²
+ Dielectric loss of power wiring B}
× Increase in equivalent thermal resistance of soil in power line A due to influence of power line B (31)

Of the numerical values in the equations (30) and (31), the current values of the power wirings A and B and the loss rates of the power wirings A and B are calculated from the load characteristics. The remaining numerical values are calculated from the shape, material, burial status, etc. of the power wiring.
Using these calculated numerical values, the temperature of the power wiring A is calculated by equation (29). The temperature of the power wiring B can be calculated by the same method.

Next, the temperature of the power wiring A when the power wiring A, the power wiring B, and the power wiring C are laid in parallel in the ground is expressed by the following equation. Therefore, the temperature of the power wiring A can be calculated by the same method as described above. Further, the temperatures of the power wirings B and C can be calculated in the same manner.
Temperature of power wiring A = base temperature + temperature rising of power wiring A + temperature rising due to power wiring B relative to power wiring A + temperature rising due to power wiring C relative to power wiring A (32)
The same applies when four or more power wires are laid in parallel.

[Power wiring selection device]
FIG. 1 shows a functional block diagram of a power wiring selection device 10 (hereinafter simply referred to as “selection device”) that implements the present invention. The selection device 10 includes an input unit (input unit) 11 for inputting input information necessary for selecting a new power wiring, an arithmetic unit 19 that performs an operation based on the input information input from the input unit 11, A storage unit 12 that stores input information input from the input unit 11 and a calculation result by the calculation unit 19 and an output unit 13 that outputs a calculation result by the calculation unit 19 are provided. The calculation unit 19 includes a current calculation unit (current calculation unit) 14, a voltage variation calculation unit (voltage variation calculation unit) 15, a temperature calculation unit (temperature calculation unit) 16, and first and second update units (first items). 1 and second updating means) 17 and 18.

In the input unit 11, the resistances R ₁ and R ₂ , reactances X ₁ and X _{2 of} the existing power wiring and the new power wiring, specifications such as the number of strips, power supply voltage Vs, active power ΣP and reactive power ΣQ of the load, The installation environment of the new power wiring (in the air, pipes, troughs, etc.), in the case of burying in the ground, the wiring laying conditions such as the burying position and the specifications of the peripheral power wiring are input.

In the current calculation unit 14, the current values I ₁ and I ₂ of the existing power wiring and the new power wiring in the electric circuit in which the existing power wiring and the new power wiring are connected in parallel are obtained from the specifications of the existing power wiring and the new power wiring, the power supply It is calculated from the voltage and the active power and reactive power of the load using the above-described formula.

The voltage fluctuation calculation unit 15 calculates the voltage fluctuation amount at both ends of the existing power wiring and the existing power wiring from the specifications of the existing power wiring and the new power wiring and the calculated current values I ₁ and I _2. It is determined whether it is within the A range.

The temperature calculation unit 16 calculates the temperature of the existing power wiring and the new power wiring from the wiring laying conditions of the existing power wiring and the new power wiring and the calculated current values I ₁ and I ₂ , and each temperature is less than the allowable value B. It is judged whether there is.

In the first update unit 17, when the voltage fluctuation amount at both ends of the power wiring calculated by the voltage fluctuation calculation unit 15 exceeds the allowable value A, or the existing power wiring or the new power wiring calculated by the temperature calculation unit 16. When the temperature exceeds the allowable value B, the size or number of newly installed power wirings is updated, and processing by the current calculation unit 14, the voltage fluctuation calculation unit 15, and the temperature calculation unit 16 is executed again.

Further, in the second updating unit 18, the temperature of the existing power wiring and the new power wiring calculated by the temperature calculation unit 16 is equal to or lower than the allowable value B, and the amount of voltage fluctuation between both ends of the power wiring is within the allowable value A range. In such a case, an update to reduce the size or number of the new power wiring is performed, and the current calculation unit 14, the voltage fluctuation calculation unit 15, and the temperature calculation unit 16 are executed again, and the existing power wiring or the new power wiring When the temperature exceeds the allowable value B or when the amount of voltage fluctuation between both ends of the power wiring deviates from the allowable value A range, the temperature of the existing power wiring and the new power wiring is below the allowable value B or the voltage between both ends of the power wiring. The latest new power wiring whose fluctuation amount is within the allowable value A range is selected.

The hardware configuration of the selection device 10 is shown in FIG. As shown in the figure, the selection device 10 includes a CPU 21, a RAM 22, a ROM 23, a hard disk 24, a recording medium drive 25, a LAN adapter 26, a video adapter 27, and a keyboard 28 and a mouse 29 as input devices (input unit 11). These are connected to each other via the system bus 20. Between the CPU 21 and the system bus 20 and between the recording medium drive 25 and the system bus 20, an interface circuit, a chip set, and the like (not shown) are provided.

The CPU 21 constitutes the calculation unit 19 of the selection device 10 and temporarily stores the programs stored in the ROM 23, the hard disk 24, and the recording medium drive 25 in the RAM 22, and then sequentially reads out the programs stored in the RAM 22 to be described later. Perform various processes.

The RAM 22 loads a part of an OS (operating system) and an application program, and temporarily stores various data such as arrays and variables used when the application program is executed under the control of the CPU 21.
The ROM 23 stores a control program (so-called BIOS) for each hardware. The ROM 23 can also store a part of the OS.

The hard disk 24 constitutes the storage unit 12 of the selection device 10 and stores an OS, various application programs including programs that cause the computer to function as the selection device 10, and input / output information.
The recording medium drive 25 is a drive device that can read data on a recording medium, such as a CD-ROM drive, a DVD-ROM drive, or a DVD-R drive.

The LAN adapter 26 (network interface card) is a communication interface for connecting to a network. It is connected to an output unit 13 such as a printer (not shown) via a network.
The video adapter 27 is a so-called video graphic adapter (VGA) to which various displays (output unit 13) such as a liquid crystal display are connected.

The system bus 20 includes various system buses such as a PCI bus and an AGP bus, and the system buses are usually connected to each other via a so-called chip set.

[Power wiring selection method]
Next, a procedure for selecting a new power wiring (power wiring selection method) executed by the selection device 10 will be described with reference to the flowchart of FIG.
(B1) From the input unit 11, the resistances R ₁ and R _{2 of} the existing power wiring and the new power wiring, the reactances X ₁ and X ₂ , specifications such as the number of strips, the power supply voltage Vs, the active power ΣP of the load, and the reactive power ΣQ is input (ST1).
(B2) In the current calculation unit 14, the current values I ₁ and I ₂ of the existing power wiring and the new power wiring in the electric circuit in which the existing power wiring and the new power wiring are connected in parallel are the values of the existing power wiring and the new power wiring. It is calculated using the above-mentioned formula from the original, the power supply voltage, and the active power and reactive power of the load (ST2).

(B3) The voltage fluctuation calculation unit 15 calculates the voltage fluctuation amount at both ends of the power wiring from the specifications of the existing power wiring and the new power wiring and the calculated current values I ₁ and I ₂ (ST3), and the voltage fluctuation amount is It is determined whether the value is within the allowable value A range (ST4).
(B4) When the voltage fluctuation amount exceeds the allowable value A, the first updating unit 17 performs updating to increase the size or number of the new power wiring (ST8), and returns to (B2). On the other hand, when the voltage fluctuation amount is within the allowable value A range, wiring laying conditions such as the laying environment of the new power wiring are input from the input unit 11 (ST5).

(B5) The temperature calculating unit 16 calculates the temperature of the existing power wiring and the new power wiring from the wiring laying conditions of the existing power wiring and the new power wiring and the calculated current values I ₁ and I ₂ (ST6). It is determined whether the temperature of the wiring and the new power wiring is equal to or lower than the allowable value B (ST7).

(B6) If the temperature of the existing power wiring or the new power wiring exceeds the allowable value B, it is further determined whether or not the update for reducing the size or number of the new power wiring was performed last time (ST9).
(B7) If no update to reduce the size or number of new power wirings has been performed last time, the first update unit 17 performs an update to increase the size or number of new power wirings (ST8), ( Return to B2). Conversely, if the previous update was performed to reduce the size or number of the new power wiring, the temperature of the existing power wiring or the new power wiring would be reduced when the temperature of the existing power wiring or the new power wiring exceeded the allowable value B. The latest new power wiring whose temperature is the allowable value B or less is selected.

(B8) On the other hand, when the temperature of the existing power wiring or the new power wiring is equal to or lower than the allowable value B, it is further determined whether or not the update for increasing the size or number of the new power wiring was performed last time (ST11).
(B9) If the update or the number of new power wirings has not been increased last time, the second update unit 18 performs the update to reduce the size or number of new power wirings (ST10), ( Return to B2). On the other hand, if the update was performed last time to increase the size or number of the new power wiring, the temperature of the existing power wiring or the new power wiring will be exceeded when the temperature of the existing power wiring or the new power wiring exceeds the allowable value B. The latest new power wiring whose temperature is the allowable value B or less is selected.

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and is within the scope of matters described in the claims. Other possible embodiments and modifications are also included. For example, in the above embodiment, the second update unit is provided, but the second update unit may be omitted. However, if the second update means is omitted, the specifications of the new power wiring are sequentially input to the selection device to check whether the temperature and voltage fluctuations of the existing power wiring and the new power wiring are within the allowable range. There is a need to.

The following conditions were set, and the effectiveness of the power wiring selection method according to the present embodiment was verified.
(A) Voltage class: 6.6 kV,
(B) Existing load: maximum 290A, (c) New load: maximum 180A (loss rate: 0.7),
(D) Load specifications when existing load and new load are combined: maximum 470A, power factor 80%,
(E) Installation environment: underground electrical conduit,
(F) Specifications of existing power wiring: CuCV3c, 250 sq, 500 m,
(G) Specifications of new power wiring: Only the length of 550 m is determined (h) Allowable temperature of existing power wiring and new power wiring: 90 ° C
(I) Voltage fluctuation tolerance: 3%

Table 1 shows a list of calculation results. According to the table, when the cross-sectional area of the new power wiring is 60 (sq) or 100 (sq), the temperature of the existing power wiring exceeds 90 ° C, but the cross-sectional area of the new power wiring is 150 (sq). The allowable temperature of the existing power wiring and the new power wiring is 90 ° C. or lower, and the voltage fluctuation amount is 0.53%. Therefore, there is no problem in both the temperature and the voltage fluctuation amount, and 150 (sq) may be selected as the optimum new power wiring.

10: selection device (power wiring selection device), 11: input unit (input means), 12: storage unit, 13: output unit, 14: current calculation unit (current calculation unit), 15: voltage fluctuation calculation unit (voltage) Fluctuation calculation means), 16: temperature calculation section (temperature calculation means), 17: first update section (first update means), 18: second update section (second update means), 19: calculation section , 20: system bus, 21: CPU, 22: RAM, 23: ROM, 24: hard disk, 25: recording medium drive, 26: LAN adapter, 27: video adapter, 28: keyboard, 29: mouse

Claims (5)

A method for selecting power wiring to be newly installed in parallel to existing power wiring,
1) a first input step for inputting 1) resistance value, reactance value, number of strips, 2) power supply voltage, and 3) active power and reactive power of the existing power wiring and the new power wiring; ,
The current value of the existing power wiring and the new power wiring in the electric circuit in which the existing power wiring and the new power wiring are connected in parallel, the specifications of the existing power wiring and the new power wiring, the power supply voltage, and the A current calculation step for calculating from the active power and reactive power of the load;
Whether the voltage fluctuation amount at both ends of the existing power wiring and the existing power wiring is calculated from the specifications of the existing power wiring and the new power wiring and the calculated current values, and is the voltage fluctuation amount within the allowable value A range? Voltage fluctuation calculating step for determining whether or not
A second input step of inputting wiring laying conditions such as a laying environment and a buried position of the existing power wiring and the new power wiring;
The temperature of the existing power wiring and the new power wiring is calculated from the wiring laying conditions of the existing power wiring and the new power wiring and the calculated current values, and it is determined whether or not each temperature is equal to or less than the allowable value B. A temperature calculating step,
The voltage fluctuation amount at both ends of the existing and new power wiring calculated in the voltage fluctuation calculation step exceeds the allowable value A, or the temperature of the existing power wiring or the new power wiring calculated in the temperature calculation step The power wiring is provided with a first update step that updates the size or number of the new power wiring when the value exceeds the allowable value B, and executes again from the current calculation step. Selection method. 2. The method for selecting a power wiring according to claim 1, wherein when the temperature of the existing power wiring and the new power wiring calculated in the temperature calculating step is equal to or less than the allowable value B, the size or condition of the new power wiring is determined. Update the number to be reduced, and execute again from the current calculation step, and when the temperature of the existing power wiring or the new power wiring exceeds the allowable value B, the existing power wiring and the new power wiring A power wiring selection method comprising a second update step of selecting the latest new power wiring whose temperature is equal to or lower than the allowable value B. A power wiring selection device newly installed in parallel to the existing power wiring,
1) Specifications of resistance value, reactance value, and number of strips of the existing power wiring and the new power wiring, 2) power supply voltage, 3) active power and reactive power of the load, and 4) the existing power wiring and the above An input means for inputting wiring laying conditions such as the laying environment and burying position of the new power wiring;
The current value of the existing power wiring and the new power wiring in the electric circuit in which the existing power wiring and the new power wiring are connected in parallel, the specifications of the existing power wiring and the new power wiring, the power supply voltage, and the Current calculating means for calculating from active power and reactive power of the load;
Whether the voltage fluctuation amount at both ends of the existing power wiring and the existing power wiring is calculated from the specifications of the existing power wiring and the new power wiring and the calculated current values, and is the voltage fluctuation amount within the allowable value A range? Voltage fluctuation calculating means for determining whether or not
The temperature of the existing power wiring and the new power wiring is calculated from the wiring laying conditions of the existing power wiring and the new power wiring and the calculated current values, and it is determined whether or not each temperature is equal to or less than the allowable value B. Temperature calculating means to
The voltage fluctuation amount at both ends of the existing and new power wirings calculated by the voltage fluctuation calculation means exceeds the allowable value A, or the temperature of the existing power wiring or the new power wiring calculated by the temperature calculation means And a first updating unit that updates the size or number of the newly installed power wiring when the value exceeds the allowable value B, and executes the current calculating unit again. Selection equipment. 4. The power wiring selection device according to claim 3, wherein when the temperature of the existing power wiring and the new power wiring calculated by the temperature calculation means is equal to or lower than the allowable value B, the size or the condition of the new power wiring is determined. Update the number to reduce the number, execute the current calculation unit again, and when the temperature of the existing power wiring or the new power wiring exceeds the allowable value B, the existing power wiring and the new power wiring A power wiring selection device comprising: a second update means for selecting the latest new power wiring whose temperature is equal to or lower than the allowable value B. A program for causing a computer to function as the power wiring selection device according to claim 3 or 4.

Images