JPS61231465A - Ac measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the continuous measurement of AC input and to enhance measuring accuracy, by performing the storing processing of sample data by using two memories and two microcomputers while simultaneously performing operation processing. CONSTITUTION:First and second memories 6a, 6b storing sample data obtained by converting the analogue AC signals of voltage and a current to digital signals by an A/D converter 4 and first and second microcomputers (MC) 5a, 5b respectively used in data storing and operation/output processing are mounted. The microcomputer MC 5a alternately stores a sample data group in the first and second memories 6a, 6b at every cycle of AC input detected by an AC cycle detection circuit 7. The second MC 5b uses the data of the memory not using MC 5a to perform operation processing and outputs predetermined measured data. Therefore, AC input is continuously performed and operation processing is also continuously performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an alternating current measuring device used in a closed type switchboard or the like.

[Prior Art] FIG. 3 is a block diagram showing a conventional AC measuring device.
FIG. 4 is a flowchart showing an overview of the process. In Figure 3, (1) is a current-voltage conversion circuit, (2) is a multiplexer, and (4) is an analog/digital (hereinafter:
(abbreviated as A/D') conversion circuit; (5) is a microcomputer; FIG. 5 is an input signal waveform diagram, and FIG. 6 is a configuration diagram of a data memory inside the microcomputer.

Next, the operation will be explained.

In FIG. 3, the AC voltage signal e is sent to the multiplexer (2
) and then input to the A/D conversion circuit (4). A/D
The conversion circuit (4) outputs a digital signal corresponding to the analog signal. The digital signal is processed by a microcomputer (
5). On the other hand, the alternating current signal i is converted into a voltage value by the current/voltage conversion circuit (1), and then input to the microcomputer (5) in the same manner as the alternating current voltage signal e.

As shown in Fig. 5, the microcomputer (5) receives an AC input signal with one period of each voltage and current as n.
Sample, A/D convert and import, n is a multiple of 4. The input of the @ symbol is performed alternately for voltage and current, and the input value is stored on the data memory (50) of the microcomputer (5) as shown in FIG. Fifth
In the figure and FIG. 6, el, e2. ...en,
il, i2゜・-・i n is the input data value, V, I
, W, VAR, PF, WH, and VARH are measured output data obtained by arithmetic processing after input, and are voltage, current, average power, reactive power, power factor, and electric energy, respectively.

and reactive energy.

The processing for output data is performed for el, e2, .
...en, il, i2, ...in are processed during the next several cycles (determined by the processing speed and sampling number of the microcomputer (5)).

When outputting the average value of voltage and current, the calculation process is performed, and when outputting the effective value, the calculation process is performed.

Also, when calculating power.

W = (Σ e・i)/n k 1k k Performs arithmetic processing.

For reactive power, the same process as for power is performed by shifting the phase of current and voltage by 906, i.e., (Σ ei) ) / nk
Calculate as mV4n+1k $1-V4n.

Also, for the power factor, pF=w7r7Otsu7 is calculated, and for WH and VARH, W
, VAR values are assumed to be constant during the measurement period, and integration processing is performed.

In addition to processing the measurement output data, the microcomputer also controls the multiplexer (2), outputs actual data, and performs initial settings.

[Problems to be Solved by the Invention] Since the conventional AC measuring device is configured as described above, the AC input cannot be continuously measured, and the input during calculation processing is not processed. Therefore, when it comes to measuring instantaneous currents or voltages and currents with complicated periodicity, there is a drawback that measurement accuracy is low.

This invention was made to solve the above-mentioned problems, and aims to provide an AC measuring device that can continuously measure AC input and has high measurement accuracy.

[Means for Solving the Problems] The AC measurement device according to the present invention is provided with two memories for data storage so that sample data can be stored and processed while arithmetic processing can be performed at the same time. There are also 2 for data storage and 2 for calculation/output processing.
These are provided separately.

[Operation] In the present invention, the first microcomputer alternately stores sample data groups in two memories for each cycle of AC input. On the other hand, the second microcomputer
Performs arithmetic processing using data in the memory that is not being used by the first microcomputer; therefore,
AC input is continuously input, and arithmetic processing is also performed continuously.

[Example 1 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, (1) is a current/voltage conversion circuit that converts current input into voltage output, (2) is a multiplexer that selectively inputs AC input to A/D conversion circuit (4),
(3) is a sample hold circuit that keeps the input signal constant during A/D conversion, (0 is an A/D conversion circuit that converts analog AC input into a digital signal, (5a) is an A/D conversion circuit (4) The microcomputer I (5b) stores and processes the output signal from the microcomputer I (5b) into memory A (8a) or memory B (8b). This is a microcomputer (2) that performs arithmetic processing and output processing for measurement using the data contained in the microcomputer.(7) is an AC cycle detection circuit.

FIG. 2 is a timing diagram showing the processing procedure.

Since the AC input sampling process and calculation process are the same as those of the conventional AC measuring device, here, the procedure for continuously measuring and calculating the calculation output process will be described.

In the AC cycle detection circuit (7), the cycle T is determined from the input voltage.
Detects microcomputers I (5a), II (
5b). Microcomputer I (5a)
Then, sampling data is stored alternately in memory A (8a) and memory B (8b) at a period T as shown in FIG. On the other hand, microcomputer n (sb)
are the same (as shown in Fig. 2, the sampling data (el, e2, . . . ) stored in the memory that is not used by the microcomputer I (5a)
en, it, i2, . . . In) is used to perform calculation processing and output processing for one or all of current, voltage, electric power, reactive power, electric energy, reactive electric energy, and power factor.

In the above embodiment, the AC input cycle is measured by the AC cycle detection circuit (7), but this may be omitted and the microcomputer I (5a) may be used to manage time, or the voltage input value may be measured by the microcomputer I (5a). The judgment may be made based on the sampling contents.

Further, although the above embodiment describes the measurement processing of voltage and current, it is also possible to apply the present invention to protection relays and the like by changing the input elements.

[Effects of the Invention] As described above, according to the present invention, an AC input can be continuously input and arithmetic processed, and a highly accurate AC measuring device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the AC measuring device according to the present invention, FIG. 2 is a timing diagram showing the processing procedure, FIG. 3 is a block diagram showing a conventional AC measuring device, and FIG. A flowchart showing an outline of the processing contents in the figure,
FIG. 5 is an input waveform diagram, and FIG. 6 is a configuration diagram of a data memory inside the microcomputer. (4) ・A/D conversion circuit, (5a), (5b)
・-Microcomputer, (ea), (13b)
···memory. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) An analog-to-digital conversion circuit that converts analog AC signals of voltage and current into digital signals, first and second memories that store sample data that is the output signal of this analog-to-digital conversion circuit; A first microcomputer that stores and processes sample data groups alternately at the cycle of an AC signal in two memories, and a memory that is not used by the first microcomputer among the two memories. and a second microcomputer that performs arithmetic processing using a group of sample data for one period of an AC signal and outputs predetermined measurement data.