JPS63124713A - Self-checking circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention performs automatic inspection of an analog input circuit in a digital protection relay device, and is intended to accurately check the phase shift of the analog input circuit. It is.

[Background of the invention]

As described in Electric Kyodo Research, Vol. 41, No. 4, "Digital Relay," page 72, Figure 5-2-2, the conventional device applies a test current from a dedicated inspection source during automatic inspection, and performs the test in advance. The attempt was made to detect a malfunction in the analog input section by comparing the size with the data written to read-only memory (RQM). However, in terms of detection sensitivity, 1
The setting is 0 to 40%, and if there is a phase shift in the input circuit, it is difficult to detect this.

[Purpose of the invention]

An object of the present invention is to provide a highly accurate automatic inspection circuit by making it possible to check not only the circuit amplification degree, that is, the size, but also the phase shift as a malfunction in an analog input circuit. .

[Summary of the invention]

In order to check not only the size but also the phase shift, since it is affected by the current in the system during automatic inspection, the current in the system immediately before automatic inspection is memorized, and the inspection current applied from the inspection power supply during inspection is set to this value. Therefore, the stored current is canceled out from this superimposed current composite value, and only the inspection current component is extracted.

Since the extracted inspection current is applied to each phase as an in-phase component, it is possible to check the phase shift of the analog input section by detecting the phase difference between these phases.

[Embodiments of the invention]

FIG. 1 shows the overall configuration of a device embodying the present invention. Currents flowing through power transmission lines L1 to L8 are connected to current transformers CT1 to CTδ.
into the input circuit of the device. First, auxiliary current transformer A
X, CTI~, and the output thereof is converted from an analog quantity to a digital quantity by a filter F, a multiplexer MPX sample holder SH, and an analog-to-digital converter AD. The automatic inspection control of the present invention is executed using the converted digital quantity by the arithmetic unit.

On the other hand, during automatic inspection, auxiliary relay contact IX closes,
The inspection current is input from the inspection power supply PT to the auxiliary circuit CT,
It is applied to the inspection windings of AxCT 1-4.

Now, FIG. 2 shows a flowchart of the control contents executed by the arithmetic unit CPU.

First, an inspection start determination routine 100 determines whether or not inspection is to be started, and if not, a branch signal N causes processing other than inspection to be executed by RY. If the inspection is to start, the following inspection processes are executed from the branch signal Y.

First, a current value storage routine 101 calculates and stores the current magnitude before inspection. Continue with current value phase storage routine 1
The phase is calculated and stored using 02.

Phase memorization requires several calculations for a certain reference quantity.1 Normally, the system voltage is introduced into the relay device, so if one of these quantities is used as a reference, this phase memorization cannot be performed. I can do it.

After storing the magnitude and phase of the current before inspection, inspection signal application control is executed by the 1st inspection signal application routine 103. Specifically, the auxiliary relay contact IX shown in Figure 1
Operate and apply check current. When the check current is applied, the check current is added to the grid current, so 1
In the next tidal current correction calculation routine 104, only the inspection current is extracted and calculated from the composite current component using the stored current data. Thereafter, a phase difference is calculated using the extracted data by a phase-to-phase absolute value check routine 105 and a phase-to-phase phase difference check routine 106. These calculation results are set in advance, and a scheduled value determination routine 107 determines whether or not the calculated values are the scheduled values. If it is good, 109 will notify you that the hardware is normal, if it is abnormal, 108
This will notify you of a hardware failure.

〔Effect of the invention〕

According to the present invention, although conventionally only the magnitude of current could be checked, phase shifts can also be detected, and a highly accurate inspection circuit can be realized.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG. 2 is a flowchart illustrating a specific calculation means and detection method. Ax, CTC~,...Auxiliary current transformer, PT...Inspection power supply, CPU...Arithmetic unit.

Claims (1)

[Claims] 1. An automatic inspection circuit characterized in that the circuit for applying the inspection current is equipped with a circuit for storing the current in the system immediately before inspection and a circuit for calculating the magnitude and phase difference between each phase.