JPH07308018A - Automatic supervisory circuit having failure locating function - Google Patents

Abstract

PURPOSE:To eliminate the unprotected state of a system by locking the system protective function in case of internal failure and producing only an alarm in case of external failure. CONSTITUTION:In case of a failure in a system 1, PT, CT2 or a cable 13, the inspection current matches a normal value and a decision circuit 15 in a CPU8 decides that the failure has occurred externally. When the input current or voltage is abnormal due to a failure in a transformer 4, a filter 6, or an A/D converter 7, the inspection current does not match the normal value and the decision circuit 15 decides that the failure has occurred internally. A relay 16 is turned ON for the external failure whereas relays 16, 17 are turned ON for the internal failure to lock the alarm and system protective functions thus eliminating unprotected state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog monitor circuit as opposed to a monitor system of an automatic monitor circuit in a digital relay device.

[0002]

2. Description of the Related Art An analog monitoring circuit for a digital relay device is disclosed in Electric Cooperative Research, Vol. 41, No. 4, P62-P6.
The PT, CT, PT, CT circuits (cable, input conversion) of the PT and CT circuits of the constant monitoring method described in 3 ), Input auxiliary transformer, filter circuit, sample hold circuit, analog multiplexer circuit, A
It monitors for abnormalities in input current and voltage values caused by failures in the hardware such as the / D conversion circuit. When a conventional digital relay device detects an abnormality in the input current or voltage value by analog monitoring, it locks the system protection function and issues a display alarm, or handles only a display alarm.

Similarly, in the analog inspection, the failure of the analog circuit in the device is detected by the method described in the same electric cooperative research, P72, but in this case, due to the system fluctuation during the analog inspection. There are cases where unnecessary detection is performed. However, since the analog inspection performed when the analog monitoring failure is detected according to the present invention is performed when the analog input continuously changes due to the analog monitoring method, both the analog monitoring and the inspection due to the system fluctuation. However, in this case, the system protection function operates properly.

[0004]

The analog monitoring circuit is
The current and voltage information of the system is taken into the CPU, and the current,
Since the abnormality is detected by the voltage value, it is impossible to determine whether the cause of the abnormality detection is inside or outside the device.

When a device lock and a display alarm are adopted as a coping method of the digital relay device at the time of the above-mentioned analog abnormality check, the device is locked by unnecessary detection of analog monitoring due to reverse phase current, voltage or current fluctuation of system phenomenon. There is. In addition, such unnecessary detection and main PT, CT
When analog monitoring failure is detected due to a cause external to the digital relay device such as a short circuit fault, the digital relay related to the system may be locked and the system may fall into an unprotected state. However, if only the display alarm is adopted to prevent the device lock, the system protection function may malfunction due to a failure of the input converter or the like.

An object of the present invention is to discriminate a method of coping with a digital relay device when an analog abnormality is detected by making it possible to determine whether the fault part is inside or outside the digital relay device.

[0007]

In order to achieve the above object, the present invention focuses on the fact that the analog inspection detects only the failure of the current / voltage value input conversion circuit in the digital relay device. By performing an analog inspection when a voltage value abnormality is detected, it is possible to determine whether the fault location causing this abnormality is inside or outside the digital relay device.

[0008]

[Function] The analog inspection to be carried out when the analog monitoring fails is performed by the main P on the system side outside the digital relay device.
When a failure occurs in T, CT, a cable, etc., the normality of the device is detected, and when a failure occurs in the current / voltage value input conversion circuit inside the device, the device failure is detected.

According to this method, when the analog inspection detects that the device is normal, only a warning is displayed as a coping method for the digital relay device, and when an abnormal device is detected, the system protection function lock and Carry out an alarm display. According to the above method, when an external failure of the digital relay device that inputs an abnormal value of current or voltage value to the digital relay device associated with the system, these digital relay devices may be locked. Will only display an alarm to prevent the protection system from falling into an unprotected state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Information on the current and voltage of the system 1 is obtained from the main units PT and C.
It is input to the digital relay device 3 by T2. The analog values of input current and voltage are the transformer 5 of the input converter 4.
Is converted into a voltage level that can be easily handled by the electronic circuit of this apparatus, and is quantized in time series by the filter 6 and the A / D circuit 7 to become a digital value. This digital value is monitored by the monitoring calculation unit 9 in the CPU 8 for correctness by checking the balance of current and voltage (balance monitoring) and the target coordinate method (reverse phase monitoring). When the monitoring calculation unit 9 detects an abnormality in the input current and voltage values, the inspection calculation unit 10 closes the switch 11, applies the inspection current from the inspection power supply 12, and writes the inspection current value in the ROM 14 in advance. Compare with a predetermined value (normal value). The cause of abnormality detection is system 1 or main unit P
If the T, CT2 or the cable 13 is defective, the inspection current value matches the normal value, and the determination circuit unit 1 in the CPU 8
5 determines that the failure location is outside the device. In addition, the cause of abnormality of the input current and voltage value is converter 4, filter 6, A /
If any of the D circuits 7 has a failure, the inspection current value does not match the normal value, and the determination circuit unit 15 in the CPU 8 determines that the failure location is inside the device.

The judgment circuit section 15 in the CPU 8 turns on the relay 16 and outputs an alarm display when it determines that the failure location is outside the apparatus, and when it determines that the failure location is inside the apparatus,
The relay 16 and the relay 17 are turned on and the alarm display and the system protection function lock are implemented.

[0013]

By performing an analog inspection when an analog monitoring abnormality is detected, it is possible to determine whether the fault location causing the abnormality in the current or voltage value is inside or outside the digital relay device, and the fault outside the device. At this time, by not locking the system protection function, it is possible to prevent all digital relay devices related to the system from being locked and the protection system from falling into an unprotected state.

Further, since it is possible to determine whether the failure location is inside or outside the digital relay device, it becomes easy to investigate the cause of the failure and maintainability is improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a failure location determination circuit according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Protected system, 2 ... Main unit PT, CT, 3 ... Digital relay device, 4 ... Input converter, 5 ... Transformer, 6 ... Filter, 7 ... A / D circuit, 8 ... CPU, 9 ... Monitoring calculation Department,
10 ... Inspection calculation unit, 11 ... Switch, 12 ... Inspection power supply, 1
3 ... Cable, 14 ... ROM, 15 ... Judgment circuit section, 1
6, 17 ... Relay.

Claims (1)

[Claims] 1. An analog monitoring circuit for detecting an abnormality of a current / voltage value input conversion circuit in a main PT, CT, a cable and a digital relay device on the system side according to input current and voltage values, and in the digital relay device. Apply the inspection current from the input converter, and use the input data and R
In a digital relay device having an analog inspection circuit that detects an abnormality in the current / voltage value input conversion circuit by comparing the predetermined value written in the OM, the cause of the abnormality is obtained by performing an analog inspection when an abnormality is detected in analog monitoring. Including the automatic monitoring circuit that makes it possible to determine whether the fault location that is inside the digital relay device is inside or outside, and when the fault location is inside the device, lock the system protection function to move to the system due to malfunction of the protection function. The digital relay device is characterized by continuing the system protection function by preventing the influence of the above and displaying only an alarm when outside the device.