JPS6150412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that can easily, accurately, and quickly detect a failure in a component of an analog-to-digital converter in a power system protection control system.

In systems where power system protection and control are performed by data processing devices such as computers, the individual reliability of each element that makes up the system greatly affects system operation and data reliability. It is necessary to thoroughly check the reliability of the components and whether the data input for calculations is correct.

In this type of power system protection control system using a computer, the amount of electricity is detected by multiple analog sensors such as transformers installed on power transmission and distribution lines, and each detected analog signal is converted into a digital signal. The analog signals detected at that time are converted and input into a computer to perform calculations for protection control. , after being filtered by a filter, sampled at a certain time interval by a sampling hold circuit, and holding the instantaneous value, these hold output signals are time-divisionally outputted by a multiplexer, and then installed at the subsequent stage. Digital output signals are obtained in a time-division manner using an analog-to-digital converter. In such a conversion device that converts multiple input analog signals into digital signals, means are employed to automatically monitor data defects due to failures of components constituting the conversion device.
As a monitoring method, a method as shown in FIG. 1 has conventionally been proposed.

That is, in the figure, each analog signal a ₁ , a ₂ ...a _o detected by a plurality of analog sensors 11, 12 ... 1n is passed through an active filter circuit 21, 22 ... 2n, respectively. As a result, frequency components that cause aliasing errors due to noise and sampling are removed and input to the respective sampling and holding circuits 31, 32, . . . , 3n. 1 is a pulse generation circuit, and this generation circuit 1
has the function of generating a clock and a constant sampling frequency, and by its output,
Analog signals input to the sampling circuits 31, 32...3n are sampled and held. The hold output signals a ₁₁ , a _{12 .} . . a _1o of the hold circuits ₃₁ , ₃₂ . a _2o , and further via a comparison circuit 4, this digital quantity is sent to a data processing circuit 5 such as a computer in a time-sharing manner.
This is what is entered in the .

Then, as mentioned above, there is a defect in the data input to the data processing circuit 5 (i.e., a defect in the component).
In order to automatically monitor the
a ₁ , a _{2 .} The comparator circuit ₄ converts the digital quantities a ₂₁ , a _{22 .} . . Absolute value of difference from ₁ | b ₁ −
The comparison circuit 4 compares A| with a preset value K, and if it becomes larger than the set value K, it is determined that a defect has occurred in the analog-to-digital converter.

The above analog arithmetic circuit 6 is generally shown in FIG.
As shown in the figure, it consists of an adder using a commonly used unbalanced operational amplifier.

In the conventional monitoring system described above, analog calculations for multiple inputs are performed by an adder using an unbalanced type arithmetic amplifier as shown in Figure 1A, so countermeasures against offset and drift of the arithmetic amplifier are required. In addition, since the analog calculation circuit 6 is for adding a ₁ , _{a 2} . Not only does the withstand voltage increase, but also the output voltage of the analog calculation circuit 6 increases.
There are drawbacks such as problems with the withstand voltage of the filter circuit 7 and the sampling and hold circuit 8.

SUMMARY OF THE INVENTION An object of the present invention is to provide a monitoring device for an analog-to-digital converter that eliminates the above-mentioned drawbacks, simplifies the circuit, improves accuracy, and can be configured with a low-voltage filter circuit.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts or corresponding parts, and the parts different from FIG. As shown in Figure A, analog sensors 11, 12, such as transformers, etc.
...1n analog quantities are taken out in parallel from each output side and connected in series in an analog signal synthesis section 9 to synthesize signals. By doing this, all n sets of analog quantities a ₁ , a ₂ . _. . , multiplexer circuit 2, and analog-to-digital converter 3, time-divisionally converts the digital quantity C ₁
Convert to The converted digital quantity _C1 is input to the comparator circuit 4, and in this comparator circuit 4,
_The absolute value of the difference between the digital quantities a ₂₁ , a _{22 .} For example, it is determined that a failure has occurred in the analog-to-digital converter.

As described above, according to the present invention, the analog arithmetic circuit 6 of FIG. 1 is not required, and the comparison set value can be reduced accordingly, improving the accuracy of comparison monitoring.

FIG. 3 shows another embodiment. This embodiment is particularly effective when the withstand voltage of the filter circuit 7 is a problem, and the analog sensors 11, 1
By appropriately connecting the series interconnections of 2, 13...1n with opposite polarity at any part, it is possible to easily suppress their combined value to below the withstand voltage of the filter circuit 7. .

As described above, according to the present invention, the output sides of the analog sensors 11, 12...1n are simply connected in series, and the detected analog signals are directly added. This eliminates the need for analog arithmetic circuits and reduces the number of components for defect monitoring, improving accuracy, making it simple and inexpensive, and making it possible to connect any sensor output side as in the embodiment shown in Figure 3. , by connecting them with opposite polarities, it has excellent effects such as being able to suppress the withstand voltage of the filter circuit and the sampling and holding circuit to a low level.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing a conventional monitoring analog-to-digital converter, FIG. 1A is a configuration diagram of a conventional analog calculation circuit, and FIG. 2 is a connection diagram showing an embodiment of the present invention. Figure 2A is a configuration diagram of an analog signal synthesis section according to an embodiment of the present invention;
The figure is a connection diagram showing another embodiment. 11, 12, 13...1n is an analog sensor,
21, 22, 23...2n and 7 are filter circuits, 31, 32, 33...3n and 8 are sampling and hold circuits, 1 is a pulse generation circuit, 2 is a multiplexer circuit, 3 is an analog-digital converter, and 4 is a Comparison circuit, 5, data processing circuit, 9
is the analog signal synthesis section.

Claims (1)

[Claims] 1. Analog signals detected by a plurality of analog sensors are applied to respective sampling and holding circuits through filter circuits, and each sampling and holding circuit samples and holds the signals at fixed time intervals. Each output is time-divisionally outputted by a multiplexer and inputted to an analog-to-digital converter, and the output signal of the converter is introduced to a data processing device to perform data processing. A comparison circuit is provided on the output side of the digital converter, and this comparison circuit derives the sum A of the output signals of the analog-to-digital converter.The output sides of the analog sensors are connected in series with each other, and each analog An analog signal synthesis section for synthesizing the outputs of the sensors is provided, and the synthesized signal from this synthesis section is introduced into a sampling hold circuit via a filter circuit, and the output signal ₁ of this hold circuit is sent to the multiplexer and the analog signal.
Digital signal C ₁ through digital converter
is introduced into the comparator circuit, and the comparator circuit compares the absolute value of the difference between the signals _C1 and A with a preset constant to determine data defects. Analog with monitoring
Digital conversion device. 2. The analog-to-digital converter with monitoring according to claim 1, wherein in the combining section, arbitrary output sides of the analog sensors are connected with opposite polarity.