JPH05312855A - Data logger - Google Patents

Abstract

PURPOSE:To provide a data logger which can automatically correct the measured value which is proportional to the consumed electric power and makes it possible to measure electric power highly precisely. CONSTITUTION:The output value proportional to the consumed electric power value obtained through an analog input circuit 52 is integrated by an instant electric power integrating counter 54. A computing circuit 55 computes the error of the consumed electric power value based on the integrated value, the count value of an integration time counter 56, and the measured value proportional to the consumed electric power obtained through a pulse input circuit 51 and corresponding to the error computed by a correction circuit 57, the consumed electric power value is automatically corrected.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to data loggers.

[0002]

2. Description of the Related Art FIG. 4 shows a configuration diagram of power measurement at a power receiving end in a general power consumer.

In FIG. 1, a transaction electricity meter 1 integrates and measures the amount of electricity used by a consumer. In addition to pay-as-you-go rates, large-scale electricity consumers have contracts with electric power companies for maximum amount of usage for each fixed time period (usually 30 minutes). If the maximum amount is exceeded, a penalty will be paid to the electric power company. It will be. A maximum demand power meter 2 is installed to measure the usage amount for each time period. The maximum demand electricity meter 2 advances the guide by a pulse proportional to the amount of electricity used from the transaction electricity meter 1.

The pulse from the transaction electricity meter 1 is
It is also supplied to customers via the pulse separator 3. Since a consumer must pay a penalty if the usage amount for each time limit exceeds the contract, for example, a device called a demand monitoring control device 4 is often installed by the consumer.

Recently, many customers have introduced the data logger 5 for automation of power management at the power receiving end, improvement in accuracy, and labor saving. That is, various transducers 6 are used for inputting to the data logger 5 in addition to the conventional pointer type meters such as current, voltage and wattmeter. It came to be used for purposes. For example, an alarm is issued when the measured power value exceeds a certain value.

[0006]

Generally, the accuracy of the transducer 6 is about ± 2%. This accuracy is guaranteed by the rated input, and the accuracy decreases as the input decreases.

[0007] For example, in the case of a customer with a contract power of about 300 to 500 Kw, PT is generally 6600V / 110.
V and CT are 50A / 5A, and the power transducer is rated at 110V and 5A. In this case, if the customer has a contract power of 300 Kw, the power applied to the transducer is about half of the rated input, and the accuracy is inevitably lowered. The data logger did not have the ability to improve accuracy. An object of the present invention is to provide a data logger that enables automatic correction and can obtain highly accurate measurement values.

[0008]

To achieve the above object, the present invention comprises an input means for inputting a signal proportional to the power used, an integrating means for integrating the signals from the input means, and an electric energy generating means. The calculating means calculates the error of the weighing value from the integrating means on the basis of the signal proportional to the electric power consumption of, and the correcting means corrects the weighing value of the integrating means on the basis of the signal from the calculating means.

[0009]

In such a structure, when the integrating means integrates the used power value for a fixed time, the calculating means calculates and corrects the error of the integrated value based on the signal proportional to the used power amount from the power amount generating means. Since the integrated value is corrected by the means so as to eliminate the error, automatic correction is possible.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the data logger of the present invention. In FIG. 1, reference numeral 51 denotes a pulse input circuit, which inputs a pulse signal proportional to the amount of electric power used, which is output from an electric energy meter with a transmitter (not shown). Reference numeral 52 denotes an analog input circuit for inputting a power consumption signal for a fixed time period of a maximum demand power meter (not shown), and sampling the power consumption signal by a clock pulse of a reference clock generator 53. For example, an A / D converter is used.

Reference numeral 54 is an instantaneous power integration counter, which integrates the output value of the analog input circuit 52. 55 is an arithmetic circuit,
The power consumption value is calculated from the signal from the pulse input circuit 51, the integrated value from the instantaneous power integration counter 54, and the count value of the integration number counter 56 that counts the integration number based on the number of clock pulse generations of the reference clock generation unit 53. Calculate the error of. Reference numeral 57 is a correction circuit, which is an arithmetic circuit 5.
A numerical value corresponding to the value of the error from 5 is registered in the registration unit 58,
The power consumption value obtained through the analog input circuit 52 is corrected while being adjusted by the conversion calculation unit 59. Next, the operation will be specifically described. The characteristics of the transducer differ depending on the product, but in general, the relationship between the output value V of the transducer and the true value P is as follows.

[0013]

## EQU1 ## P = f (v) In the data logger of the present invention, error measurement is first performed and then function data as shown in equation (1) is created.

The error measurement will be described with reference to FIG. Since the watt-hour meter with a transmitter (watt-hour meter for transaction) is guaranteed to have an accuracy of ± 1% and is substantially higher than that, this output value is used as the true value P.

FIG. 2 is a diagram showing the relationship between the change in the instantaneous power from the transducer and the pulse interval of the pulse signal proportional to the amount of power used from the power meter with the transmitter. Figure 2
In Fig. 2, when the power load increases, the value of the instantaneous power increases as in the first half of Fig. 2 (a), and the pulse interval becomes narrower as in the first half of Fig. 2 (b). On the other hand, when the power load decreases,
(B) The pulse interval becomes longer as in the latter half. by the way,
When the instantaneous power is sampled and integrated at fine intervals and the error is zero in both the transducer that measures the instantaneous power and the watt hour meter with the transmitter, the instantaneous power integrated value for each pulse interval in FIG. 2B is always the same. It becomes a value. That is,
The shaded areas in FIG. 2A have the same value. Specifically, the output pulse from the transaction electricity meter is
If the pulse constant of 00p / kWh and the transducer is 0-1kW / 0-5V, 1
The electric energy per pulse interval is 1/2000 kWh. As an output of the reference clock generator 53, data sampling from the transducer is performed every 10 ms, and 0-5 V is converted to 0-1000 for internal processing. If an integrated value is X, a sampling value per pulse interval. The integrated value is as follows.

[0016]

[Equation 2] This is the reference value.

Next, the registered value of the registration unit 58 of the correction circuit 57 will be described. First, when a pulse signal is input from the transaction electricity meter, the integrated value of the instantaneous power integration counter 54,
The count value of the integration counter 56 is set to zero.

After that, as the processing of the arithmetic circuit 55 of the data logger 5, the instantaneous power value is sampled and integrated periodically (for example, every 10 ms or 1 ms), and the count value of the integration counter 56 is incremented by one. Then, when the pulse is next input from the transaction electricity meter,
Calculate the error by the following formula.

[0019]

[Equation 3] Further, the output value V and the true value P of the transducer in the equation (1)
Is calculated by the following equation.

[0020]

[Equation 4] This is registered as shown in FIG. In the example of FIG. 3, the size of the registration unit 58 is 1000. For example, if V is 3.365V,

[0021]

[Equation 5] 3.365 × 1000 ÷ 5 = 673, and P is registered at the 673rd element of the registration unit 58.
To register. The above registration work is performed from actual data during actual operation.

On the other hand, for example, the display of the instantaneous power on the display device of the data logger 5 is performed as follows. The data logger 5 displays periodically sampled data on its display unit, and performs the sampling every momentary power. That is, the instantaneous power is corrected and calculated in the correction circuit 57 as follows and displayed in real time. If the sampled data has already been registered in the registration unit 58, the converted value can be obtained and is displayed. If it is not in the registration unit 58, the conversion calculation unit 59 obtains data by interpolation and displays it. For example, if the read voltage is 3.5V and the conversion values at 3.3V and 3.6V are registered in the registration unit 58, the conversion value can be obtained by linear interpolation. After that, the same operation is repeated to correct the data from the transducer.

[0023]

As described above, according to the present invention, the calculating means calculates the error of the integrated value of the signal, which is proportional to the electric power used, which is integrated by the integrating means, based on the measured value from the electric energy generating means. Since the integrated value is corrected according to the error calculated by the correction means, the output value of the transducer can be automatically corrected and a data logger capable of highly accurate power measurement can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a data logger according to the present invention.

FIG. 2 is an explanatory diagram of error measurement of the data logger of the present invention.

FIG. 3 is an explanatory diagram of a correction operation of the data logger of the present invention.

FIG. 4 is a system diagram showing general power measurement.

[Explanation of symbols]

1 …… Transaction electricity meter, 2 …… Maximum demand electricity meter, 5 ……
Data logger 54 ... Instantaneous power integration counter, 55 ... Arithmetic circuit, 5
7 ... Correction circuit

Claims (1)

[Claims] 1. An input means for inputting a signal proportional to the electric power used, an integrating means for accumulating the signals from the input means, and the integrating means based on the signal proportional to the electric power used from the electric energy generating means. A data logger having a calculating means for calculating an error of the measured value from the calculating means and a correcting means for correcting the measured value of the integrating means based on a signal from the calculating means.