JP2520714B2 - Inspection and monitoring system for input circuits of digital protective relays - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an inspection / monitoring system for an input circuit of a digital protection relay device, which determines whether the input circuit of the digital protection relay device is defective.

[Prior art]

FIG. 3 is a schematic block diagram showing an inspection and monitoring system of an input circuit of a conventional digital type protective relay device disclosed in, for example, Japanese Patent Laid-Open No. 60-55820, in which 1 is a current of a power system. A current transformer (CT) to be taken out, 2 is an input transformer section for insulating the output of CT1 and converting the level, 3 is a filter circuit section for extracting a necessary frequency component, 4 is a filter circuit section 3
An analog-digital converter (A / D converter) that converts the output of the to a digital value, 5 is a central processing unit (CPU) that performs relay calculation and system faults and whether the input circuit is good or bad.
Is. FIG. 4 is a detailed block diagram of the filter circuit unit 6, where 6 is a filter, and 7 is a multiplexer (MPX) for selecting and outputting the output of the filter 6. FIG. 5 is a block diagram of an input circuit of a digital protective relay device including a plurality of filter circuits 3a to 3c. 3a, 3b and 3c are filter circuits (filter cards), 4 is A / D conversion. In the section, 71 is a multiplexer (MPX) that selects and outputs the output of each filter circuit 3a to 3c, and 9 is A
It is a / D converter. Next, the operation will be described. The current of the power grid is CT1
Is taken out, is subjected to insulation and level conversion in the input transformer unit 2, and is input to the filter circuit unit 3. The required frequency component is extracted by the filter 6 of the filter circuit unit 3, and the output of each filter 6 is switched and output from the MPX 7 at any time. The output analog quantity is analog-to-digital converted by the A / D converter 4. As shown in FIG. 5, the outputs of many filter circuits 3a to 3c are connected to the A / D conversion unit 4, and each output is switched and selected by the MPX71, and digitally converted by the A / D converter 9. Convert to a value. Using this digital value as input data, CPU5 performs relay calculation and system fault judgment,
System protection. At the same time, is performed quality determination of the input circuit using the above input data the CPU 5, for example, 3-phase valid check as a determination method _{(A + B + C -3 O} = ε,
It adopts a method of _{A + B + C -3 O =} ε) or the like. The outline of the 3-phase valid check method is as follows: A phase, B phase
The vector sum of phase C and phase C is usually zero, but if a hardware failure occurs in one of the three phases,
Phase + phase + phase is not zero, and abnormality is detected when it is no longer zero. Here, the same phenomenon occurs in the case of a system fault other than the abnormality of the input circuit, but the duration of the abnormality is monitored for distinction. That is, after the occurrence of the system fault, if the abnormality continues even after the time required for the recovery elapses, it is determined that the input circuit is abnormal.

[Problems to be Solved by the Invention]

Since the conventional method of checking and monitoring the input circuit of the digital protective relay is configured as described above, the relay calculation and the system failure determination are erroneously performed during the period until the failure of the input circuit is detected. No need for relays,
If the selection of the filter cards 3a to 3c is incorrect and the arrangements of both the filter cards 3a to 3c are the same, the phase + phase + phase becomes zero and the monitoring state of the input circuit becomes normal. In spite of the fact that there is a voltage input to the original current input location and there is a case where an excess current is flowing, the unnecessary operation of the relay that can prevent the occurrence of it if monitoring is normal occurs. There was a problem of causing it. The present invention has been made in order to solve the above problems, and it is possible to prevent an unnecessary operation of a relay and to quickly diagnose a defective portion of an input circuit, which is an input circuit of a digital protective relay device. The purpose is to obtain an inspection and monitoring system.

[Means for Solving the Problems]

An inspection / monitoring system of an input circuit of a digital protective relay device according to the present invention applies an inspection / monitoring voltage to filters corresponding to different channels of a plurality of filter cards, and a filter circuit and A It is provided with a comparison circuit for comparing the output passing through the / D conversion unit with a predetermined reference value.

[Action]

The comparison circuit in the present invention compares the reference value output when the filter and the A / D conversion unit of the channel through which the output of the inspection and monitoring power supply has passed with the actual output, and if they do not match, the input circuit It is judged to be defective, and relay calculation and system failure judgment are stopped.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. The block diagrams shown in FIGS. 3 and 4 are the same as the block diagrams in the embodiment of the present invention. FIG. 1 is a block diagram of an input circuit according to an embodiment of the present invention. In the figure, 8 is a power supply for inspection and monitoring which outputs a voltage for inspection and monitoring at a constant level, and is used for the filter 6 of channel 1 in the first filter card 3a and channel 2 in the second filter card 3b.
To the filter 6 of channel n in the third filter card 3c. Here, the CPU 5 shown in FIG. 3 is also a comparison circuit for comparing the digital value obtained by A / D converting the output of the filter 6 of the channel to which the inspection and monitoring power supply is connected with the reference. Next, the operation will be described with reference to the flowchart of FIG. The electric current of the electric power system is taken out by CT1, is insulated and level-converted by the input transformer unit 2, and is input to the filter circuit unit 3. Next, the required frequency component is extracted by the filter 6 of the filter circuit unit 3 and input to a predetermined channel of the MPX7. The MPX7 performs channel switching at any time, and the output of the filter 6 is input to the A / D conversion unit 4. In the A / D converter 4, first, the output of the filter cards 3a to 3c is changed to MP at any time.
It is selected by X71 and converted into a digital value by the A / D converter 9.
Using this digital value as input data, the CPU 5 performs relay calculation and system fault judgment, and protects the system in the event of a system fault. On the other hand, a certain level of inspection and monitoring voltage is applied to each filter card 3a to 3c in a filter of a channel that is not used for relay calculation and a different channel for each filter card 3a to 3c. This constant level voltage is selected by the MPX7 and MPX71, and the A / D
It is converted into a digital value by the converter 9. In this case, the inspection and monitoring power supply 8 is connected so that a constant level voltage is applied to the channel 1 of the first filter card 3a, the channel 2 of the second filter card 3b, and the channel n of the third filter card 3c. , The output of the filter 6 of the channel 1 of the first filter card 3a to the CPU5, the second filter card
When the digital value obtained by A / D converting the output of the filter 6 of the channel 2 of 3b and the output of the filter 6 of the channel n of the third filter card 3c is input, these values and a constant level voltage are A / D converted. The value (reference value) is compared (steps ST1 to ST3), and if they all match, it is determined that the input circuit is normal, and relay calculation is executed based on other digital values (step ST4). ). However, if there is a value that does not match even one, it is determined that the input circuit is abnormal and other digital values are not used, that is, relay calculation is not performed and the determination of the system fault is stopped (step ST5). . Although the constant level voltage is used as the inspection and monitoring voltage in the above embodiment, it may be zero voltage or AC voltage. Also, different voltage values may be applied to the filter cards 3a to 3b. In addition, in the above embodiment, the continuous monitoring is explained,
The operation according to the flowchart of FIG. 2 may be performed at the time of inspection, and the same effect as that of the above-described embodiment is obtained. Further, in the above embodiment, the inspection and monitoring voltage is applied from the outside of the filter cards 3a to 3c, but it may be applied from the inside of the filter cards 3a to 3c.

As described above, according to the present invention, the inspection and monitoring system of the input circuit of the digital protection relay device in which the plurality of filter circuits are provided in the input circuit is applied to the filters of different channels of the plurality of filter cards. Since the inspection and monitoring voltage is applied to, and the output digital value of the corresponding input circuit is compared with the reference value to detect the abnormality of the input circuit,
The quality of the filter selection operation in the filter circuit and the filter circuit output selection operation in the analog / digital converter can be judged immediately without affecting the system fault judgment. In particular, the selection of the filter circuit by the analog / digital converter is possible. Since the quality of the operation can also be determined, there is an effect that it is possible to prevent the malfunction of the system fault determination due to the erroneous selection of the filter circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing an input circuit of a digital protective relay device according to an embodiment of the present invention, and FIG. 2 is a flowchart showing an operation of an inspection / monitoring system of an input circuit of a digital protective relay device. FIG. 4 is a schematic block diagram showing an inspection / monitoring system of an input circuit of a digital type protective relay device.
FIG. 5 is a detailed block diagram of a filter circuit section, and FIG. 5 is a block diagram showing an input circuit of a conventional digital protective relay device. 1 is a current transformer (transformer for measuring instrument), 2 is an input transformer section, 3
Is a filter circuit unit, 3a to 3c are filter circuits (filter cards), 4 is an A / D conversion unit, 5 is a CPU (arithmetic circuit, comparison circuit), 6 is a filter, 7,71 is a multiplexer (MPX),
8 is a power supply for inspection and monitoring, and 9 is an A / D converter. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A plurality of instrument transformers for taking in electric quantities of an electric power system, and a plurality of filters each of which includes a filter corresponding to a plurality of channels for extracting necessary frequency components of the taken-in electric quantities and selectively outputting each filter output. An input circuit including an analog-digital conversion unit for selecting the output of each filter circuit and analog-digital conversion by selecting the output of the filter circuit, and detecting an accident in the power system based on the output of the analog-digital conversion unit, In the inspection and monitoring method of the input circuit of the digital type protective relay device having an arithmetic circuit for inspecting and monitoring the input circuit,
Dedicated channels for inspection and monitoring are provided respectively on different channels of the plurality of filter circuits, and a voltage for inspection and monitoring is input to a filter corresponding to the dedicated channel for inspection and monitoring, and the arithmetic circuit corresponds to the dedicated channel for inspection and monitoring. The output value of the filter is input through the analog / digital conversion unit, and the output value is compared with a predetermined reference value of the inspection / monitoring voltage to determine whether the selection operation of the plurality of filter circuits of the input circuit is good or bad. A method for inspecting and monitoring an input circuit of a digital protective relay device, which comprises a comparison circuit for judging whether or not the input signal is a digital protection relay device.