JP2017142183A - Power measurement device and power measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power measurement device which can accurately measure power supplied from a solar cell power conditioner to a commercial power system.SOLUTION: A power measurement device 6 calculates generated electric power P21 by P21=P2×{V11+V12+R1×(I11×cosθ11+I12×cosθ12)+2×R2×I2}/(V11+V12). V11 is a voltage between a first voltage line L11 and a neutral line N1 of a voltage line 3 for a distribution board. V12 is a voltage between a second voltage line L12 and the neutral line N1 of the voltage line 3 for the distribution board. R1 is the wiring resistance of the voltage line 3 for the distribution board. I11 is a current flowing in the voltage line L11. I12 is a current flowing in the voltage line L12. R2 is the wiring resistance of a voltage line 2 for a PV. I2 is a current flowing in the voltage line 2 for the PV. P2 is the generated electric power of a PV-PCS 4. P21 is the corrected generated electric power of the PV-PCS 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power measuring device and a power measuring method connected to a distribution board installed in a building or a home.

  The conventional power generation system shown in Patent Document 1 includes a power sale watt-hour meter that measures the amount of power sold to a power company using power generated using natural energy.

  A power measuring device typified by the electricity sales electricity meter is generally installed on a distribution board. Then, the power measuring device includes a phase voltage between the first voltage line and the neutral line of the single-phase three-wire main voltage line connected to the distribution board in the building or house, and the second voltage Voltage measurement input means for measuring the phase voltage between the voltage line and the neutral line, and a plurality of current sensors for measuring the current flowing from the distribution board to the load side are provided.

  The voltage measurement input means is generally connected to a distribution board. The load is an electrical device or a home appliance installed in a building or a house, and is connected to a distribution board.

  The power measuring device configured as described above can accurately measure the power supplied to the load by using the voltage measurement input means and the plurality of current sensors.

JP 2014-135855 A

  In a configuration in which the total amount of power generated by a solar power conditioner installed in a building or house is purchased by a commercial system, a single-phase three-wire main voltage line is connected to a distribution board, and a single-phase three-wire main A branch voltage line branched from the voltage line is connected to the solar battery power conditioner.

  In such wiring, the wiring resistance of the voltage line from the branch point of the single-phase three-wire main voltage line and the branch voltage line to the distribution board and the wiring resistance from the branch point to the solar cell power conditioner are Exists. Therefore, the voltage measured by the voltage measurement input means installed on the distribution board is a value lower by the voltage drop due to these wiring resistances. That is, the power output from the solar battery power conditioner and the power measured by the power measuring device are different values.

  Therefore, the power measuring device used in the conventional power generation system shown in Patent Document 1 cannot accurately measure the power supplied from the solar cell power conditioner to the commercial system. Therefore, in the conventional power generation system, in order to measure the generated power of the solar battery power conditioner at the time of purchasing the entire amount, it is necessary to install another power measuring device at the installation location of the solar battery power conditioner.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the electric power measuring apparatus which can measure correctly the electric power supplied to a commercial system from a solar cell power conditioner.

  In order to solve the above-described problems and achieve the object, the power measurement device of the present invention is a power measurement device that is connected to a distribution board and measures generated power, and is a single-phase 3 connected to a commercial system. Among the main voltage lines of the line, the voltage between the first voltage line connected to the distribution board and the neutral line is V11, the current flowing through the first voltage line is I11, and calculation is performed from V11 and I11. The power factor of the first voltage line to be set is cos θ11, and the voltage between the second voltage line connected to the distribution board and the neutral line is V12 among the main voltage lines of the single phase three lines, The current flowing through the second voltage line is set as I12, the power factor of the second voltage line calculated from V12 and I12 is set as cos θ12, and the main voltage line is branched from the single-phase three-line main voltage line. The current flowing through the connected branch voltage line is I2, and the main voltage of the single-phase three-wire Of the solar cell power conditioner calculated based on I2, V11, and V12, where R1 is the wiring resistance of the voltage line from the branch point of the line and the branch voltage line to the distribution board, and R2 is the wiring resistance of the branch voltage line. When the generated power is P2, and the generated power of the solar cell power conditioner obtained by correcting P2 is P21, P21 is P21 = P2 × {V11 + V12 + R1 × (I11 × coss θ11 + I12 × cos θ12) + 2 × R2 × I2} / (V11 + V12).

  According to the present invention, it is possible to accurately measure the power supplied from the solar battery power conditioner to the commercial system.

The figure which shows the electric power measuring device which concerns on embodiment of this invention, the solar cell power conditioner of a whole quantity purchase structure, and a distribution board. The figure which shows the structural example of the electric power measurement apparatus shown in FIG. The flowchart which shows operation | movement of the electric power measurement apparatus shown in FIG. The figure which shows an example of the resistance data hold | maintained at the wiring resistance calculating part shown in FIG. The figure which shows the hardware structural example for implement | achieving the parameter input part, wiring resistance calculating part, electric power calculating part, and electric power correction part which are shown in FIG.

  Hereinafter, a power measuring device and a power measuring method according to an embodiment of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram showing a power measuring device, a solar cell power conditioner having a total purchase configuration, and a distribution board according to an embodiment of the present invention.

  A solar cell power conditioner (PV-PCS) 4 shown in FIG. 1 is installed in a building or a house. PV-PCS4 converts the direct-current power output from the solar cell panel which is not shown in figure into alternating current power, and outputs it. One end of a PV voltage line 2 which is three branch voltage lines is connected to the PV-PCS 4. The other end of the branch voltage line is connected to the main voltage line 1 of a single-phase three line.

  The first voltage line L21 in the PV voltage line 2 is connected to the first voltage line L11 in the single-phase three-wire mains voltage line 1 connected to the commercial system 20.

  The second voltage line L22 in the PV voltage line 2 is connected to the second voltage line L12 in the single-phase three-line main voltage line 1 connected to the commercial system 20. A neutral line N2 in the PV voltage line 2 is connected to a neutral line N1 in the single-phase three-line main voltage line 1 connected to the commercial system 20.

  In general, the current output from the PV-PCS 4 does not flow through the neutral line N1, but flows through the first voltage line L21 and the second voltage line L22. And since the value of the electric current which flows into the 1st voltage line L21 and the 2nd voltage line L22 is equal, what is necessary is just to provide one current sensor in the voltage line 2 for PV.

  In the present embodiment, a CT (Current Transformer) 2 that is a current sensor is provided on the first voltage line L21. CT2 measures the alternating current I2 that is output from the PV-PCS 4 and flows through the first voltage line L21, and outputs the measured value. The measured value of the alternating current I2 detected by CT2 is input to the power measuring device 6.

  In the present embodiment, the AC voltage applied between the first voltage line L21 and the neutral line N2 is V21, and the AC voltage applied between the second voltage line L22 and the neutral line N2 is V22. .

  The first voltage line L11, the neutral line N1, and the second voltage line L12 are connected to the primary side of a main switch (not shown) provided in the distribution board 5.

  A distribution board voltage line 3 shown in FIG. 1 is a part of the main voltage line 1, and is a voltage line provided from a branch point a between the main voltage line 1 and the PV voltage line 2 to the distribution board 5. is there.

  CT11 is provided in the 1st voltage line L11 of the voltage line 3 for distribution boards. CT11 measures the alternating current I11 which flows into the 1st voltage line L11 of the voltage line 3 for distribution boards, and outputs the measured value.

  CT12 is provided in the 2nd voltage line L12 of the voltage line 3 for distribution boards. CT12 measures the alternating current I12 which flows into the 2nd voltage line L12 of the voltage line 3 for distribution boards, and outputs the measured value.

  Depending on the installation environment of the electrical equipment, that is, the installation position of the PV-PCS 4, the installation position of the distribution board 5, or the position of the branch point a, the length of the voltage line 2 for PV and the length of the voltage line 3 for distribution board are several. It varies from m to several tens of meters.

  In the present embodiment, the wiring resistance per distribution board voltage line 3 from the branch point a to the distribution board 5 is R1, and 1 of the PV voltage line 2 from the branch point a to PV-PCS4. The wiring resistance per book is R2.

  The power measuring device 6 includes three voltage input terminals V1, V2, and V3. The voltage input terminal V1 is connected to a first voltage line L11 wired in the distribution board 5. The voltage input terminal V2 is connected to a neutral line N1 wired in the distribution board 5. The voltage input terminal V3 is connected to a second voltage line L12 wired in the distribution board 5.

  The power measuring device 6 measures an AC voltage applied between the voltage input terminal V1 and the voltage input terminal V2, that is, an AC voltage V11 applied between the first voltage line L11 and the neutral line N1. . The power measuring device 6 measures an AC voltage applied between the voltage input terminal V3 and the voltage input terminal V2, that is, an AC voltage V12 applied between the second voltage line L12 and the neutral line N1. To do. The AC voltages V11 and V12 are measured by a voltage measuring unit (not shown) in the power measuring device 6.

  The power measuring device 6 calculates the generated power P2 generated by the PV-PCS 4 as P2 = (V11 + V12) × I2. However, the AC voltage V11 calculated in this way is lower than the AC voltage V21 detected at the AC output terminal of the PV-PCS 4 by a voltage drop in the PV voltage line 2 and the distribution board voltage line 3. Become. Similarly, the AC voltage V12 is lower than the AC voltage V22 detected at the AC output terminal of the PV-PCS 4 by a voltage drop in the PV voltage line 2 and the distribution board voltage line 3.

  Therefore, the power measuring device 6 cannot accurately calculate the generated power P2 of the PV-PCS 4 only by the measured value of the alternating current I2 and the measured values of the AC voltages V11 and V12.

  Hereinafter, a configuration example for accurately calculating the generated power P2 of the PV-PCS 4 will be described.

  FIG. 2 is a diagram illustrating a configuration example of the power measurement device illustrated in FIG. 1. FIG. 3 is a flowchart showing the operation of the power measuring apparatus shown in FIG. FIG. 4 is a diagram showing an example of resistance data held by the wiring resistance calculation unit shown in FIG.

  As shown in FIG. 2, the power measurement device 6 according to the present embodiment includes a parameter input unit 7, a wiring resistance calculation unit 8, a power calculation unit 9, a power correction unit 10, and a measurement value input unit 11.

  The parameter input unit 7 may be an interface connectable to a network such as the Internet or an intranet, or may be an interface connectable to a device such as a personal computer, a smartphone, or a tablet terminal.

  The wiring resistance calculation unit 8 holds in advance resistance data 30 regarding the PV voltage line 2 and the distribution board voltage line 3 shown in FIG. 4, and the wiring resistance corresponding to each parameter input from the parameter input unit 7. R1 and R2 are calculated. As shown in FIG. 4, in the resistance data 30, the type of wiring, the nominal cross-sectional area of the wiring, and the resistance value per 1 m of the wiring are recorded in association with each other.

  The measurement value input unit 11 inputs the measurement values of the alternating currents I2, I11, and I12 and the measurement values of the AC voltages V11 and V12 measured by a voltage measurement unit (not shown) in the power measurement device 6 in real time. Are transmitted to the power calculation unit 9 and the power correction unit 10.

  The power calculation unit 9 calculates the AC power P11 supplied via the first voltage line L11 and the power factor cos θ11 of the first voltage line L11 based on the measured values of the AC current I11 and the AC voltage V11. Further, the power calculation unit 9 calculates the AC power P12 supplied via the second voltage line L12 and the power factor cos θ12 of the second voltage line L12 based on the measured values of the AC current I12 and the AC voltage V12. . Furthermore, the power calculation unit 9 calculates the generated power P2 output from the PV-PCS 4 based on the measured values of the AC current I2, the AC voltage V11, and the AC voltage V12.

  The power factor cos θ11 of the first voltage line L11 and the power factor cos θ12 of the second voltage line L12 may be simply set to cos θ11 = cos θ12 = 1. However, the calculation including the power factors cos θ11 and cos θ12 can calculate the corrected generated power P21 described later with higher accuracy.

  The power correction unit 10 corrects the generated power P2 calculated by the power calculation unit 9 based on the measured value transmitted from the measured value input unit 11, and calculates the corrected generated power P21.

  The operation of the power measuring device 6 will be described below.

  Parameters regarding the PV voltage line 2 and the distribution board voltage line 3 are input by the installer or user of the power measuring device 6. As an example of the parameter, there is information on the wiring type and wiring length of the PV voltage line 2 and the distribution board voltage line 3. However, the parameters are not limited to these, and the wiring diameters of the PV voltage line 2 and the distribution board voltage line 3 may be included.

  For example, information such as the wiring type “CV cable”, the wiring length “10 m”, and the wiring diameter “22 sq” is input to the parameter input unit 7 as parameters of the PV voltage line 2. Information such as the wiring type “CV cable”, the wiring length “20 m”, and the wiring diameter “22 sq” is input to the parameter input unit 7 as parameters of the distribution board voltage line 3.

  In the wiring resistance calculation unit 8, wiring resistances R1 and R2 corresponding to each parameter transmitted from the parameter input unit 7 are calculated (S1). Specifically, when data such as “CV cable”, “22 sq”, and “10 m” are input as parameters related to the PV voltage line 2 and the distribution board voltage line 3, the wiring resistance calculation unit 8 The wiring resistances R1 and R2 are calculated by checking the data against the resistance data 30.

  In the power calculation unit 9, AC power P11, power factor cos θ11 of the first voltage line L11, AC power P12, and power factor cos θ12 of the second voltage line L12 are calculated (S2). Moreover, in the electric power calculating part 9, the generated electric power P2 output from PV-PCS4 is calculated (S3).

The power correction unit 10 calculates the corrected generated power P21 by the following equation (1) (S4).
P21 = P2 × {V11 + V12 + R1 × (I11 × cos θ11 + I12 × cos θ12) + 2 × R2 × I2} / (V11 + V12) (1)

V11, V12, R1, I11, cos θ11, I12, cos θ12, R2, and I2 shown in the above formula (1) are as follows.
(A) V11 is a voltage between the first voltage line L11 of the distribution board voltage line 3 connected to the distribution board 5 and the neutral line N1.
(B) V12 is a voltage between the second voltage line L12 of the distribution board voltage line 3 connected to the distribution board 5 and the neutral line N1.
(C) R1 is the wiring resistance of the distribution board voltage line 3, which is a voltage line from the branch point a to the distribution board 5.
(D) I11 is a current flowing through the first voltage line L11.
(E) cos θ11 is a power factor of the first voltage line L11 calculated from the alternating current I11 and the alternating voltage V11.
(F) I12 is a current flowing through the second voltage line L12.
(G) cos θ12 is a power factor of the second voltage line L12 calculated from the AC voltage V12 and the AC current I12.
(H) R2 is the wiring resistance of the PV voltage line 2.
(I) I2 is a current flowing through the PV voltage line 2.
(J) P2 is the generated power of the PV-PCS 4 calculated based on the alternating current I2, the alternating voltage V11, and the alternating voltage V12.
(K) P21 is the generated power of PV-PCS4 obtained by correcting P2.

  FIG. 5 is a diagram illustrating a hardware configuration example for realizing the parameter input unit, the wiring resistance calculation unit, the power calculation unit, and the power correction unit illustrated in FIG. 2.

  The parameter input unit 7, the wiring resistance calculation unit 8, the power calculation unit 9, the power correction unit 10, and the measurement value input unit 11 are a memory including a processor 51 and a RAM (Random Access Memory) or a ROM (Read Only Memory). 52 and an input / output interface 53 for connecting to a network.

  The processor 51, the memory 52, and the input / output interface 53 are connected to the bus 50 and transmit information to each other via the bus 50.

  For example, the parameter input unit 7 and the measured value input unit 11 are realized by the input / output interface 53. The input / output interface 53 includes the parameters described above, the measured values of the alternating currents I11, I12, and I2 measured by CT11, CT12, and CT2, and the alternating voltage V11 measured by a voltage measurement unit (not shown) in the power measuring device 6. , V12 when the measured value is input.

  The input / output interface 53 is also used when outputting the corrected power information of the generated power P21 calculated by the power correction unit 10 to a display (not shown). The said display provides the electric power generation amount generated with PV-PCS4 with respect to the user in a building or a house.

  When realizing the wiring resistance calculation unit 8, the power calculation unit 9, and the power correction unit 10, a program for the wiring resistance calculation unit 8, a program for the power calculation unit 9, and a program for the power correction unit 10 are stored in the memory 52. In addition, when the processor 51 executes these programs, the wiring resistance calculation unit 8, the power calculation unit 9, and the power correction unit 10 are realized.

  As described above, according to the power measuring device 6 according to the present embodiment, in the PV voltage line 2 connected to the PV-PCS 4 and the distribution board voltage line 3 connected to the distribution board 5. Even when the voltage applied to the distribution board 5 is different from the voltage at the output terminal of the PV-PCS 4 due to the voltage drop, the error of the generated power P2 of the PV-PCS 4 due to the voltage drop is corrected, and the generated power after correction is corrected. P21 can be calculated.

  Therefore, in order to measure the generated power of the PV-PCS 4 in the total quantity purchase configuration, it is not necessary to additionally install the power measuring means similar to the power measuring device 6 in the PV-PCS 4. Therefore, work such as installation work and wiring work for providing the power measuring means becomes unnecessary, and not only the work cost can be reduced, but also maintenance of the power measuring means becomes unnecessary, so that the maintenance cost can be reduced.

  The power measuring apparatus 6 according to the present embodiment further includes a parameter input unit 7 for inputting parameters relating to the distribution board voltage line 3 and parameters relating to the PV voltage line 2 from the branch point a to the distribution board 5. . By providing the parameter input unit 7, the generated power P can be corrected according to the installation environment of the electrical equipment. Therefore, the error of the generated power P calculated by the power measuring device 6 can be further reduced as compared with the configuration without the parameter input unit 7.

  The power measuring device 6 according to the present embodiment includes a wiring resistance calculation unit 8 that calculates the wiring resistance R1 and the wiring resistance R2 based on the parameters input to the parameter input unit 7. By providing the wiring resistance calculation unit 8, the wiring resistances R1 and R2 can be calculated based on information that can be intuitively set by the user, such as the wiring type, the nominal cross-sectional area of the wiring, and the wiring resistivity as shown in FIG. It becomes. Accordingly, the convenience of the user is improved as compared with the configuration not including the wiring resistance calculation unit 8, and the calculation of the wiring resistances R1 and R2 can be performed based on more detailed parameters, so that the error of the generated power P can be further reduced.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 main voltage line, 2 voltage line for PV, 3 voltage line for distribution board, 4 PV-PCS, 5 distribution board, 6 power measuring device, 7 parameter input section, 8 wiring resistance calculation section, 9 power calculation section, 10 power correction unit, 11 measured value input unit, 20 commercial system, 30 resistance data, 50 bus, 51 processor, 52 memory, 53 input / output interface, I11, I12, I2 AC current, L11, L21 first voltage line, L12, L22 Second voltage line, N1, N2 neutral line, P generated power, P11, P12 AC power, P2, P21 generated power, R1, R2 wiring resistance, V1, V2, V3 voltage input terminal, V11, V12 , V21, V22 AC voltage, a branch point.

Claims (4)

A power measuring device that is connected to a distribution board and measures generated power,
Among the single-phase three-wire mains voltage lines connected to the commercial system, the voltage between the first voltage line connected to the distribution board and the neutral line is V11,
The current flowing through the first voltage line is I11,
The power factor of the first voltage line calculated from V11 and I11 is cos θ11,
Among the main voltage lines, the voltage between the second voltage line connected to the distribution board and the neutral line is V12,
The current flowing through the second voltage line is I12,
The power factor of the second voltage line calculated from V12 and I12 is cos θ12,
The current branched from the main voltage line and flowing through the branch voltage line connected to the solar battery power conditioner is I2.
R1 is the wiring resistance of the voltage line from the branch point of the main voltage line and the branch voltage line to the distribution board,
The wiring resistance of the branch voltage line is R2,
The generated power of the solar cell power conditioner calculated based on I2, V11, and V12 is P2,
When the generated power of the solar cell power conditioner obtained by correcting the P2 is P21,
A power measuring device that calculates P21 by P21 = P2 × {V11 + V12 + R1 × (I11 × coss θ11 + I12 × cos θ12) + 2 × R2 × I2} / (V11 + V12).   The power measuring device according to claim 1, further comprising a parameter input unit configured to input a parameter of a voltage line from the branch point to the distribution board and a parameter of the branch voltage line.   The power measurement device according to claim 2, further comprising: a wiring resistance calculation unit that calculates the R1 and the R2 based on the two parameters input to the parameter input unit. A power measurement method that includes a wiring resistance calculation unit, a power calculation unit, and a power correction unit, and is executed by a power measurement device that measures the generated power that is connected to the distribution board and purchased in the commercial system.
Of the single-phase three-wire mains voltage lines connected to the commercial system, the voltage between the first voltage line connected to the distribution board and the neutral line is V11,
The current flowing through the first voltage line is I11,
The power factor of the first voltage line calculated from V11 and I11 is cos θ11,
Among the main voltage lines, the voltage between the second voltage line connected to the distribution board and the neutral line is V12,
The current flowing through the second voltage line is I12,
The power factor of the second voltage line calculated from V12 and I12 is cos θ12,
The current branched from the main voltage line and flowing through the branch voltage line connected to the solar battery power conditioner is I2.
R1 is the wiring resistance of the voltage line from the branch point of the main voltage line and the branch voltage line to the distribution board,
The wiring resistance of the branch voltage line is R2,
The generated power of the solar cell power conditioner calculated based on I2, V11, and V12 is P2,
When the generated power of the solar cell power conditioner obtained by correcting the P2 is P21,
The wiring resistance calculation unit calculates the R1 and the R2,
The power calculation unit calculates the P2,
The power correction unit uses the R1 and R2 calculated by the wiring resistance calculation unit to change the P21 to P21 = P2 × {V11 + V12 + R1 × (I11 × coss θ11 + I12 × cos θ12) + 2 × R2 × I2} / (V11 + V12) Power measurement method to calculate with.

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