JPH09113540A - Electric power measuring device of system connecting power source system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure bidirectional electric power by a single electric power measuring transducer by using a system connecting power source system having a solar battery or the like as a power source as an object. SOLUTION: An electric power measuring transducer 6 to output electric power sent in one direction through a power line as a positive measuring signal and electric power sent in its inverse direction as a negative measuring signal, is provided in the power line extending up to a connecting point to a commercial electric power system from a connecting point of an in-house load. The electric power measuring transducer 6 is connected to an information processing device 9 to measure electric power. The information processing device 9 samples the measuring signal outputted from the electric power measuring transducer 6 at regular periods, and distinguishes positive measuring data from negative measuring data by judging a positive and a negative of measuring data obtained by this, and performes necessary operation processing on these measuring data. Its result is displayed on a display device 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grid interconnection power supply system using a solar cell or the like as a power generation source, and surplus power reversely flown to a commercial power grid and demand power supplied from the commercial power grid. The present invention relates to a power measuring device for measuring and.

[0002]

2. Description of the Related Art In recent years, a grid-connected power supply system using a solar cell (1) as a power supply has been put into practical use as shown in FIG. In the system, the DC output obtained from the solar cell (1) is converted into an AC output through the inverter (2), and then supplied to the household load (4) through the indoor power line (13), and the surplus is supplied. Electric power flows backward to the commercial power system (3). When the required output cannot be obtained from the solar cell (1), such as in the rain or at night, the commercial power system (3) supplies the shortage of power to the domestic load (4). In such a grid-connected power supply system, the power line (13) is equipped with a generated power measuring device (5) and a demand and supply power measuring device (60) on both sides of the connection point of the domestic load (4). Then, the solar cell (1) is
The surplus power that is generated by the power supply and demand power meter (60) and flows backward to the commercial power system (3) side
(Sold power) and demand power (buy power) flowing from the commercial power system (3) to the domestic load (4) are measured.

Here, since the demand and supply power measuring device (60) needs to individually integrate the selling power and the buying power, conventionally,
A sold power measurement transducer for measuring the forward power flowing through the power line (13) to the commercial power system (3) side, and a reverse power flowing through the power line (13) toward the household load (4) side The power supply (13) was equipped with two transducers, a purchased power measurement transducer for the power supply and demand (60).

[0004]

Particularly in a home-use grid-connected power supply system, there is as much space as possible for installing equipment such as a generated power measuring instrument (5) and a demand and supply power measuring instrument (60). Although it is required to omit it, the conventional power supply and demand measuring instrument
Since (60) is composed of two transducers, there is a problem that a large installation space is required.

By the way, generally, a power measuring transducer is constructed on the assumption that it is mounted on a power line through which power flows only in one direction, and a power measuring signal is always output as a positive value, but the power is reversed. There is known a so-called bidirectional power measurement transducer in which a measurement signal corresponding to the electric power is output as a negative value from a common output terminal even when the electric power flows in the direction. If such a bidirectional power measuring transducer is installed in the above-mentioned system interconnection power supply system, it is possible to measure selling power and buying power with one transducer.

In the grid-connected power supply system, in order to improve the accuracy of the power measurement data, measurement and sampling are performed in a cycle as short as possible, and the measurement data obtained by this is in units of 1 minute or 1 After integration in time units, the integration result is averaged and stored as an electric power value at that time in a memory or the like.

However, in the grid-connected power supply system, since the power generated by the solar cell (1) and the size of the domestic load (4) change every moment, the direction of the power flow of the power line (13) is short time intervals. In some cases, the reverse rotation may be repeated, which causes a problem as shown in FIG. 6, for example. That is, as shown in FIG. 6, after the power measurement signal P from the power measurement transducer is sampled every 10 seconds, the sampling data is integrated over 1 minute, and the integrated value is averaged for 1 minute. When the result is the electric power value at that time (minute), the integrated value may be 0 even though the electric power is changing between positive and negative. Therefore, the amount of power sold for this one minute
Since (+60) and the purchased power amount (-60) are buried in the arithmetic processing, a problem occurs, for example, when the sell price and the buy price per unit power amount are different.

An object of the present invention is to provide a power measuring device capable of accurately performing bidirectional power measurement with a single power measuring transducer, targeting a system interconnection power supply system using a solar cell or the like as a power source. That is.

[0009]

SUMMARY OF THE INVENTION A power measuring device according to the present invention provides a power line extending from a connection point of a domestic load to a point of interconnection with a commercial power system with positive power supplied in one direction through the power line. It is equipped with a power measurement transducer that outputs the measurement signal and the power sent in the opposite direction as a negative measurement signal from a common output terminal. The power measuring transducer is connected to the power measuring circuit. The power measurement circuit, sampling means for sampling the measurement signal output from the power measurement transducer at a constant cycle,
It comprises a judging means for judging whether the measurement data obtained by sampling is positive or negative, and an arithmetic processing means for discriminating the positive measurement data and the negative measurement data and performing necessary arithmetic processing on these measurement data.

In the above power measuring device, after the power measuring signal is sampled and before the arithmetic processing such as integration is performed, the positive / negative of each measured data is judged to determine the positive measured data and the negative measured data. Are separated and handed over individually to the arithmetic processing, so that the data is not buried by the arithmetic processing.

In a specific configuration, the arithmetic processing means includes an integration processing means for integrating the positive measurement data and the negative measurement data over a predetermined time respectively, and the processing result of the selling power amount and the buying power amount. And storage means for storing it as time series data. As a result, the amount of sold electric power and the amount of purchased electric power are sequentially stored in the storage means with the predetermined time period as a cycle. Here, if the display means is connected to the arithmetic processing means, it is possible to display the time series changes of the amount of sold power and the amount of purchased power in real time.

In another specific configuration, the arithmetic processing means integrates the positive measurement data and the negative measurement data respectively over a predetermined time, and calculates an average value of the integrated values within the predetermined time. It comprises a processing means and a storage means for storing the processing result as time series data of surplus power and demand power. As a result, the surplus power and the demand power are sequentially stored in the storage means with the predetermined time as a cycle. Here, if a display device is connected to the arithmetic processing means,
It is possible to display the time series changes of surplus power and demand power in real time. Further, by reading the surplus power and the demand power from the storage means and calculating the integrated value of each day, it is possible to obtain the sold power amount and the purchased power amount on that day.

[0013]

According to the power measuring apparatus for the grid-connected power supply system of the present invention, even when bidirectional power is measured by one power measuring transducer, the measurement data is buried due to the arithmetic processing. Since it does not happen, a highly accurate power measurement value can be obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment in which the present invention is applied to a measuring device of a photovoltaic power generation system shown in FIG. 1 will be described in detail with reference to the drawings. FIG. 2 shows the overall configuration of the measuring device, in which a solar power generation system is equipped with a measuring system (7) including a plurality of signal converters (71) and a demand and supply power measuring transducer (6). The plurality of signal converters (71), for example, take in the DC voltage and DC current output from the solar cell (1), the amount of solar radiation, the temperature, the operating status of the inverter (2),
A signal representing the state quantity is output.

On the other hand, the demand and supply power measuring transducer (6)
Is equipped as the electric power measuring device (60) shown in FIG. 1, and is connected to the commercial power system (3) from the connection point of the domestic load (4).
It is a bidirectional power measuring transducer capable of bidirectionally measuring the power flowing in the power line (13) extending to the interconnection point.

The measurement signal obtained from the measurement system (7) is A /
After being converted into a digital signal through the D converter (8), it is supplied to the information processing device (9) including a microcomputer. The information processing device (9) has a memory (10) in which a predetermined arithmetic processing procedure described later is written, and an external storage device (11) such as a hard disk device in which various measured values obtained by the arithmetic processing should be stored. And are connected. Various measured values read from the external storage device (11) are output to the display device (12) and displayed as a graph or a table.

The information processing device (9) has a measuring system at a cycle of 6 seconds.
The measurement data from (7) is sampled, the average of 10 times of the sampling data is taken, and it is written in the file of the external storage device (11) as the measurement value at the time (minute).

FIG. 3 is a transducer for measuring the power supply and demand.
The calculation processing procedure for the measurement data obtained from (6) is shown. First, in step S1, the measurement data Pi of the demand and supply power is sampled in a cycle of 6 seconds, and in step S2, it is determined whether the sampled measurement data Pi is 0 or more. If the determination result is YES, the positive measurement data Pi (+) is integrated in step S3, and if the determination result is NO, the negative measurement data Pi (+) is calculated in step S4.
Add (-). Then, in step S5, it is determined whether one minute has elapsed from the sampling in step S1. If NO, the process returns to step S1 to repeat the sampling of the power measurement data.

Thereafter, if YES is determined in the step S5, the process proceeds to a step S6, and the integration results ΣPi (+) and ΣPi (-) in the steps S3 and S4 are respectively integrated times n (n in the present embodiment). = 6) and perform averaging. Next, in step S7, the result P of the averaging process
After writing (+) and P (-) in the file as the forward power value and the backward power value, respectively, the process shifts to sampling and calculation processing of other measurement data.

FIG. 4 shows a plurality of channels CH1 to CH32 provided in a common file by executing the above procedure.
On the other hand, the forward power value P (+), the reverse power value P (-), the solar cell output voltage Vdc, ..., And the change in the temperature T are sequentially written together with the time data for every minute. It represents. Here, even when the power measurement data Pi changes as shown in FIG. 6, for example, the positive measurement data Pi as shown in FIG.
(+) And negative measurement data Pi (-) are individually added up,
Since the forward power value P (+) and the reverse power value P (-) are calculated and written in the file of FIG. 4, the data is not buried by the arithmetic processing. Therefore, by appropriately reading out the measured values from the file of FIG. 4, it is possible to display, for example, accurate time-series changes in the amount of sold power and the amount of purchased power.

By adopting the same signal processing as that of the above-described power measuring device, it is possible to configure a current measuring device which measures the current flowing in both directions by dividing it into positive measurement data and negative measurement data. Is.

The above description of the embodiments is for explaining the present invention and should not be construed as limiting the invention described in the claims or reducing the scope.
In addition, the configuration of each part of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a photovoltaic power generation system in which the present invention is implemented.

FIG. 2 is a block diagram showing a configuration of a power measuring device of the present invention.

FIG. 3 is a flowchart showing a procedure of sampling and calculation processing for power supply and demand.

FIG. 4 is a diagram illustrating a configuration of a file in which measurement results are written.

FIG. 5 is a chart for explaining a situation of sampling and integration processing of supply and demand power in the present invention.

FIG. 6 is a chart for explaining a state of sampling of conventional power supply and demand and a problem of integration processing.

[Explanation of symbols]

 (1) Solar cell (2) Inverter (3) Commercial power system (4) Domestic load (6) Demand / supply power measurement transducer (9) Information processing device (11) External storage device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Ishida 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (5)

[Claims] 1. In a system interconnection power supply system in which an AC power source is connected to a commercial power system and a household load is connected to an output end of the AC power source, from a connection point of the domestic load. The power line that extends to the point of interconnection to the commercial power system is equipped with a power measurement transducer that outputs the power sent in one direction through the power line as a positive measurement signal and the power sent in the opposite direction as a negative measurement signal. , The power measuring transducer is connected to a power measuring circuit, and the power measuring circuit judges the positive / negative of the measurement data obtained by the sampling means for sampling the measurement signal output from the power measuring transducer at a constant cycle. The judgment means and the arithmetic processing means for distinguishing the positive measurement data and the negative measurement data and performing necessary arithmetic processing on these measurement data are provided. A power measuring device for a grid-connected power supply system characterized by being equipped with. 2. The calculation processing means stores integration processing means for integrating positive measurement data and negative measurement data over a predetermined time respectively, and stores the processing result as time series data of selling power amount and buying power amount. The power measuring device according to claim 1, further comprising: 3. An arithmetic processing means, an average processing means for integrating positive measurement data and negative measurement data respectively over a predetermined time, and calculating an average value of the integrated values within the predetermined time,
The power measuring device according to claim 1, further comprising a storage unit that stores the processing result as time series data of surplus power and demand power. 4. The power measuring device according to claim 2, wherein the arithmetic processing means is connected to a display means for displaying the data stored in the storage means. 5. The AC power generation device according to claim 1, comprising a solar cell and an inverter that converts DC power obtained from the solar cell into AC power and outputs the AC power. Electric power measuring device.